Washington (CNN) Hillary Clinton met with the FBI for three and a half hours Saturday as part of the investigation into her use of a private email server while leading the State Department, her campaign said.

"Secretary Clinton gave a voluntary interview this morning about her email arrangements while she was secretary," Clinton spokesman Nick Merrill said in a statement. "She is pleased to have had the opportunity to assist the Department of Justice in bringing this review to a conclusion."

Clinton told MSNBC's Chuck Todd Saturday evening that the interview was something "I had been eager to do."

An aide said the interview occurred at FBI headquarters in Washington Saturday morning. The FBI declined to comment.

The meeting signals the investigation is coming to an end, and sources tell CNN the expectation is Clinton will not face charges.

Still, the probe has cast a shadow over Clinton's campaign, and news of FBI agents interviewing the former secretary of state gave Republicans an opportunity to pounce after Clinton has spent weeks at the top of most polls. It has also put the Justice Department in the position of having a major impact on the 2016 race -- a role made even more awkward this week by an unplanned meeting between former President Bill Clinton and Attorney General Loretta Lynch that raised questions about the impartiality of the probe.

The question now becomes how long it will take for the FBI to conclude its probe.

Within the next two weeks or so, the expectation is there will be an announcement of no charges being brought against Clinton so long as no evidence of wrongdoing emerges from her interview with the FBI, sources familiar with the investigation told CNN. CNN has previously reported no charges were expected to be brought against Clinton because the investigators had not found evidence to warrant charges, according to multiple law enforcement officials. A Democrat close to Clinton said Saturday the campaign believes the FBI will announce its decision before the conventions.

Sources familiar with the investigation had previously told CNN the Justice Department's aim was to wrap up before the Republican and Democratic conventions later this month. The timing is crucial, because if Clinton were to be indicted before the convention, Democrats could perhaps nominate another candidate.

Photos: Hillary Clinton email controversy Hillary Clinton, while U.S. secretary of state, checks her Blackberry on a military plane in October 2011. Clinton said she used a private email account for her official work at the State Department and that she did so out of convenience. But she admitted in retrospect "it would have been better" to use multiple emails. Hide Caption 1 of 7 Photos: Hillary Clinton email controversy Clinton checks her phone after addressing the U.N. Security Council in March 2012. Hide Caption 2 of 7 Photos: Hillary Clinton email controversy Clinton looks at her phone after attending a Russia-U.S. meeting in Hanoi, Vietnam, in July 2010. Hide Caption 3 of 7 Photos: Hillary Clinton email controversy Clinton types on her phone during a visit to Brasilia, Brazil, in April 2012. Hide Caption 4 of 7 Photos: Hillary Clinton email controversy Clinton hands off her phone after arriving to meet with Dutch Foreign Minister Uri Rosenthal in The Hague, Netherlands, in December 2011. Hide Caption 5 of 7 Photos: Hillary Clinton email controversy Clinton speaks on a phone in the lobby of a Honolulu hotel before briefing reporters on the Haiti earthquake in January 2010. Hide Caption 6 of 7 Photos: Hillary Clinton email controversy Clinton looks at a phone with Assistant Secretary of State for European Affairs Philip Gordon as they wait in a Munich, Germany, conference room for a bilateral meeting with the Ukrainian President in February 2012. Hide Caption 7 of 7

Asked about reports that she is unlikely to face charges, Clinton told Todd, "I am not going to comment on the process. I have no knowledge of any timelines. This is entirely up to the department."

Presumptive Republican nominee Donald Trump said it was "impossible for the FBI not to recommend criminal charges against Hillary Clinton."

"It is impossible for the FBI not to recommend criminal charges against Hillary Clinton. What she did was wrong! What Bill did was stupid!" Trump tweeted, referring to the former president's meeting with Lynch.

It is impossible for the FBI not to recommend criminal charges against Hillary Clinton. What she did was wrong! What Bill did was stupid! — Donald J. Trump (@realDonaldTrump) July 2, 2016

After reports surfaced that Clinton was unlikely to be charged, Trump then tweeted, "It was just announced-by sources-that no charges will be brought against Crooked Hillary Clinton. Like I said, the system is totally rigged!"

It was just announced-by sources-that no charges will be brought against Crooked Hillary Clinton. Like I said, the system is totally rigged! — Donald J. Trump (@realDonaldTrump) July 2, 2016

Asked by CNN's Brianna Keilar in a "State of the Union" interview Saturday about the possibility of the presumptive Democratic nominee being indicted, New Jersey senator -- and potential Clinton running mate -- Cory Booker flatly ruled out the possibility.

"That's just not going to happen," said Booker, who declined to answer whether the former secretary of state should step aside in favor of Vermont Sen. Bernie Sanders or Vice President Joe Biden if she's indicted before the election.

"That's something that, to me, is not even within the realm of possibility," Booker said.

A reminder of Clinton's trustworthiness issues

The interview comes at the end of a week that could have been another win for Clinton as Trump continues to struggle, but instead demonstrated her -- and her husband's -- inability to avoid unforced errors and leave past controversies behind.

House Benghazi Committee Republicans on Tuesday released their report on the September 11, 2012, attack where four Americans died, which drew significant media attention but lacked significant new information that changed the dynamic of the race. The panel's biggest discovery was finding the email address and server over a year ago.

Clinton has maintained that no emails marked as classified at the time were sent on the server, and that information in some emails was retroactively classified. And her campaign has actively portrayed the congressional investigation into Benghazi as a partisan exercise, highlighted by last October's 11-hour hearing where Clinton testified.

But the FBI interview, along with news of the Clinton-Lynch meeting, shows Clinton can't move past the email issue -- a story that overshadowed the launch of her campaign in early 2015 and helped Bernie Sanders find running room.

Sanders, in fact, is still in the race, pushing for progressive changes to the Democratic platform. As recently as Thursday, the Vermont senator said he's not ready to endorse Clinton.

For Republicans, the possibility of an indictment is a satisfying one. The GOP has pursued the Clintons for 25 years, from the scandals of Bill Clinton's presidency and his impeachment to Hillary Clinton's actions leading up to and during the Benghazi attacks. That the FBI could hamstring her presidential ambitions is a bonus for the GOP.

Photos: Clinton scandals through the years Hillary Clinton answers questions from reporters March 10, 2015 at the United Nations in New York. Clinton admitted that she made a mistake in choosing, for convenience, not to use an official email account when she was secretary of state. Hide Caption 1 of 13 Photos: Clinton scandals through the years The Democratic 2016 candidate is pictured here speaking to the press about a new initiative between the Clinton Foundation, the U.N. Foundation and Bloomberg Philanthropies in New York City on December 15, 2014. The Clinton Foundation confirmed on May 21, 2015, that it received as much as $26.4 million in previously unreported payments from foreign governments and corporations for paid speeches by the Clintons. It's the latest in a string of admissions from the foundation that it didn't always abide by a 2008 ethics agreement to disclose its funding sources publicly. According to foundation officials, the income -- at least $12 million and as much as more than twice that -- was not disclosed publicly because it was considered and tallied for tax purposes as revenue, rather than donations. Hide Caption 2 of 13 Photos: Clinton scandals through the years Hillary Clinton testifies before the Senate Foreign Relations Committee on Capitol Hill on January 23, 2013 in Washington, D.C. Lawmakers questioned the former secretary of state about the security failures during the September 11, 2012 attacks against the U.S. mission in Benghazi, Libya, that led to the death of four Americans, including U.S. Ambassador Christopher Stevens. Hide Caption 3 of 13 Photos: Clinton scandals through the years The Clintons at a celebration of the Breast and Cervical Cancer Act of 2000 at the White House on January 4, 2001. Weeks later, on his final day in office, Bill Clinton would pardon an unusually large number of people including fugitive Marc Rich, a move that was dubbed "Pardongate." Hide Caption 4 of 13 Photos: Clinton scandals through the years On February 12, 1999, the United States Senate voted on two articles of impeachment and acquitted former President Clinton. He was impeached by the House for perjury and obstruction of justice, related to statements he gave regarding his relationship with White House intern Monica Lewinsky. Hide Caption 5 of 13 Photos: Clinton scandals through the years Former President Clinton stands to the side as he waits to be introduced at an event at the White House on October 8, 1998. Later that afternoon, the Republican House majority adopted a motion to launch an impeachment inquiry into Clinton's presidency. Hide Caption 6 of 13 Photos: Clinton scandals through the years Former President Clinton listens to Hillary during an education event at the White House on January 26, 1998. During the event, Clinton made a statement about his alleged affair with former White House intern Monica Lewinsky. The President vehemently denied the allegations, saying, "I did not have sexual relations with that woman, Miss Lewinsky, I never told anybody to lie, not a single time." Hide Caption 7 of 13 Photos: Clinton scandals through the years On February 25, 1997, the Clinton administration released the names of 800-plus people who stayed overnight in the Lincoln Bedroom of the White House. Bill Clinton defended the practice of inviting friends and supporters to stay overnight. The White House also released several hundred pages of documents, such as this one. with his handwritten notes from Clinton enthusiastically supporting the idea. President Bill Clinton's guests in the Lincoln Bedroom gave a total of at least $5.4 million to the Democratic National Committee during 1995 and 1996, according to a study for CNN by the Campaign Study Group. Hide Caption 8 of 13 Photos: Clinton scandals through the years The Clintons opened the Centennial Olympic Games in Atlanta on July 20, 1996. A few months earlier, Hillary Clinton made a trip to Bosnia as first lady, and said she landed in the war-torn country under sniper fire. Years later, she was criticized by the Obama campaign for exaggerating her account of that trip. Hide Caption 9 of 13 Photos: Clinton scandals through the years Hillary Clinton arrives to testify before a federal grand jury in connection with the failed Whitewater land deal in Washington, D.C., on January 26, 1996. Hide Caption 10 of 13 Photos: Clinton scandals through the years This image of White House intern Monica Lewinsky standing beside President Bill Clinton at a White House function on November 17, 1995 was used as evidence in Kenneth Starr's investigation into allegations of an inappropriate relationship between the intern and Clinton. Hide Caption 11 of 13 Photos: Clinton scandals through the years The women involved in the sex scandals: Paula Jones, left, who in 1994 accused former President Clinton of sexual harassment; Monica Lewinsky, center, the former White House intern with whom former President Clinton admitted to having an "inappropriate relationship" and Gennifer Flowers, right, who claimed in 1992 to be then-presidential candidate Bill Clinton's lover. Hide Caption 12 of 13 Photos: Clinton scandals through the years President Bill Clinton speaks to a group of business leaders from the East Room of the White House on February 11, 1993. Months later, seven White House staffers were fired in a Clinton scandal dubbed "travelgate." Two years later, a Republican-led House committee approved a report concluding that the Clintons condoned the firing of staffers on the urging of Hollywood producer and big-time Clinton donor, Harry Thomason.

Hide Caption 13 of 13

Republicans pounce

Republican National Committee Chairman Reince Priebus said in a statement that Clinton is now "the first major party presidential candidate to be interviewed by the FBI as part of a criminal investigation surrounding her reckless conduct."

"That the FBI wanted her for questioning reinforces her central role in deliberately creating a culture which put her own political ambitions above State Department rules and jeopardized our national security. In over 2,000 emails, Clinton's decision exposed classified information, including 22 that included top secret intelligence, just so she could skirt transparency laws in order to hide her shady dealings as secretary of state," Priebus continued.

He added, "The American people need to have confidence that the Obama Justice Department is conducting a fair and impartial investigation, but when the attorney general meets secretly with Bill Clinton just days before Hillary's interrogation is conducted discreetly over a holiday weekend, it raises serious concerns about special treatment."

RNC chief strategist and communications director Sean Spicer also pounced on the news Saturday afternoon.

".@HillaryClinton campaign statement says She "voluntarily" met w @FBI for 3.5 hours this morning - yeah, lots of people volunteer 2 do that," he tweeted.

.@HillaryClinton campaign statement says She "voluntarily" met w @FBI for 3.5 hours this morning - yeah, lots of people volunteer 2 do that — Sean Spicer (@seanspicer) July 2, 2016

He quickly added, "Now I get it! After Attorney General @LorettaLynch & @billclinton secretly meet @HillaryClinton spends 3.5 hrs #FourthOfJulyWeekend @fbi HQ"

But the interview is a reminder for Republicans that Trump is a major liability himself. He's more unpopular than Clinton is and his poll numbers are sliding. Her campaign and allies have been airing millions of dollars' worth of ads against him, many highlighting his impolitic statements about women and minorities -- two groups that are backing Clinton by large margins.

Photos: Hillary Clinton's life in the spotlight Hillary Clinton accepts the Democratic Party's nomination for president at the Democratic National Convention in Philadelphia on July 28, 2016. The former first lady, U.S. senator and secretary of state was the first woman to lead the presidential ticket of a major political party. Hide Caption 1 of 43 Photos: Hillary Clinton's life in the spotlight Before marrying Bill Clinton, she was Hillary Rodham. Here she attends Wellesley College in Massachusetts. Her commencement speech at Wellesley's graduation ceremony in 1969 attracted national attention. After graduating, she attended Yale Law School. Hide Caption 2 of 43 Photos: Hillary Clinton's life in the spotlight Rodham was a lawyer on the House Judiciary Committee, whose work led to impeachment charges against President Richard Nixon in 1974. Hide Caption 3 of 43 Photos: Hillary Clinton's life in the spotlight In 1975, Rodham married Bill Clinton, whom she met at Yale Law School. He became the governor of Arkansas in 1978. In 1980, the couple had a daughter, Chelsea. Hide Caption 4 of 43 Photos: Hillary Clinton's life in the spotlight Arkansas' first lady, now using the name Hillary Rodham Clinton, wears her inaugural ball gown in 1985. Hide Caption 5 of 43 Photos: Hillary Clinton's life in the spotlight The Clintons celebrate Bill's inauguration in Little Rock, Arkansas, in 1991. He was governor from 1983 to 1992, when he was elected President. Hide Caption 6 of 43 Photos: Hillary Clinton's life in the spotlight Bill Clinton comforts his wife on the set of "60 Minutes" after a stage light broke loose from the ceiling and knocked her down in January 1992. Hide Caption 7 of 43 Photos: Hillary Clinton's life in the spotlight In June 1992, Clinton uses a sewing machine designed to eliminate back and wrist strain. She had just given a speech at a convention of the International Ladies' Garment Workers Union. Hide Caption 8 of 43 Photos: Hillary Clinton's life in the spotlight During the 1992 presidential campaign, Clinton jokes with her husband's running mate, Al Gore, and Gore's wife, Tipper, aboard a campaign bus. Hide Caption 9 of 43 Photos: Hillary Clinton's life in the spotlight Clinton accompanies her husband as he takes the oath of office in January 1993. Hide Caption 10 of 43 Photos: Hillary Clinton's life in the spotlight The Clintons share a laugh on Capitol Hill in 1993. Hide Caption 11 of 43 Photos: Hillary Clinton's life in the spotlight Clinton unveils the renovated Blue Room of the White House in 1995. Hide Caption 12 of 43 Photos: Hillary Clinton's life in the spotlight Clinton waves to the media in January 1996 as she arrives for an appearance before a grand jury in Washington. The first lady was subpoenaed to testify as a witness in the investigation of the Whitewater land deal in Arkansas. The Clintons' business investment was investigated, but ultimately they were cleared of any wrongdoing. Hide Caption 13 of 43 Photos: Hillary Clinton's life in the spotlight The Clintons hug as Bill is sworn in for a second term as President. Hide Caption 14 of 43 Photos: Hillary Clinton's life in the spotlight The first lady holds up a Grammy Award, which she won for her audiobook "It Takes a Village" in 1997. Hide Caption 15 of 43 Photos: Hillary Clinton's life in the spotlight The Clintons dance on a beach in the U.S. Virgin Islands in January 1998. Later that month, Bill Clinton was accused of having a sexual relationship with former White House intern Monica Lewinsky. Hide Caption 16 of 43 Photos: Hillary Clinton's life in the spotlight Clinton looks on as her husband discusses the Monica Lewinsky scandal in the Roosevelt Room of the White House on January 26, 1998. Clinton declared, "I did not have sexual relations with that woman." In August of that year, Clinton testified before a grand jury and admitted to having "inappropriate intimate contact" with Lewinsky, but he said it did not constitute sexual relations because they had not had intercourse. He was impeached in December on charges of perjury and obstruction of justice. Hide Caption 17 of 43 Photos: Hillary Clinton's life in the spotlight The first family walks with their dog, Buddy, as they leave the White House for a vacation in August 1998. Hide Caption 18 of 43 Photos: Hillary Clinton's life in the spotlight President Clinton makes a statement at the White House in December 1998, thanking members of Congress who voted against his impeachment. The Senate trial ended with an acquittal in February 1999. Hide Caption 19 of 43 Photos: Hillary Clinton's life in the spotlight Clinton announces in February 2000 that she will seek the U.S. Senate seat in New York. She was elected later that year. Hide Caption 20 of 43 Photos: Hillary Clinton's life in the spotlight Clinton makes her first appearance on the Senate Environment and Natural Resources Committee. Hide Caption 21 of 43 Photos: Hillary Clinton's life in the spotlight Sen. Clinton comforts Maren Sarkarat, a woman who lost her husband in the September 11 terrorist attacks, during a ground-zero memorial in October 2001. Hide Caption 22 of 43 Photos: Hillary Clinton's life in the spotlight Clinton holds up her book "Living History" before a signing in Auburn Hills, Michigan, in 2003. Hide Caption 23 of 43 Photos: Hillary Clinton's life in the spotlight Clinton and another presidential hopeful, U.S. Sen. Barack Obama, applaud at the start of a Democratic debate in 2007. Hide Caption 24 of 43 Photos: Hillary Clinton's life in the spotlight Obama and Clinton talk on the plane on their way to a rally in Unity, New Hampshire, in June 2008. She had recently ended her presidential campaign and endorsed Obama. Hide Caption 25 of 43 Photos: Hillary Clinton's life in the spotlight Obama is flanked by Clinton and Vice President-elect Joe Biden at a news conference in Chicago in December 2008. He had designated Clinton to be his secretary of state. Hide Caption 26 of 43 Photos: Hillary Clinton's life in the spotlight Clinton, as secretary of state, greets Russian Prime Minister Vladimir Putin during a meeting just outside Moscow in March 2010. Hide Caption 27 of 43 Photos: Hillary Clinton's life in the spotlight The Clintons pose on the day of Chelsea's wedding to Marc Mezvinsky in July 2010. Hide Caption 28 of 43 Photos: Hillary Clinton's life in the spotlight In this photo provided by the White House, Obama, Clinton, Biden and other members of the national security team receive an update on the mission against Osama bin Laden in May 2011. Hide Caption 29 of 43 Photos: Hillary Clinton's life in the spotlight Clinton checks her Blackberry inside a military plane after leaving Malta in October 2011. In 2015, The New York Times reported that Clinton exclusively used a personal email account during her time as secretary of state. The account, fed through its own server, raises security and preservation concerns. Clinton later said she used a private domain out of "convenience," but admits in retrospect "it would have been better" to use multiple emails. Hide Caption 30 of 43 Photos: Hillary Clinton's life in the spotlight Clinton arrives for a group photo before a forum with the Gulf Cooperation Council in March 2012. The forum was held in Riyadh, Saudi Arabia. Hide Caption 31 of 43 Photos: Hillary Clinton's life in the spotlight Obama and Clinton bow during the transfer-of-remains ceremony marking the return of four Americans, including U.S. Ambassador Christopher Stevens, who were killed in Benghazi, Libya, in September 2012. Hide Caption 32 of 43 Photos: Hillary Clinton's life in the spotlight Clinton ducks after a woman threw a shoe at her while she was delivering remarks at a recycling trade conference in Las Vegas in 2014. Hide Caption 33 of 43 Photos: Hillary Clinton's life in the spotlight Clinton, now running for President again, performs with Jimmy Fallon during a "Tonight Show" skit in September 2015. Hide Caption 34 of 43 Photos: Hillary Clinton's life in the spotlight Clinton testifies about the Benghazi attack during a House committee meeting in October 2015. "I would imagine I have thought more about what happened than all of you put together," she said during the 11-hour hearing. "I have lost more sleep than all of you put together. I have been wracking my brain about what more could have been done or should have been done." Months earlier, Clinton had acknowledged a "systemic breakdown" as cited by an Accountability Review Board, and she said that her department was taking additional steps to increase security at U.S. diplomatic facilities. Hide Caption 35 of 43 Photos: Hillary Clinton's life in the spotlight U.S. Sen. Bernie Sanders shares a lighthearted moment with Clinton during a Democratic presidential debate in October 2015. It came after Sanders gave his take on the Clinton email scandal. "The American people are sick and tired of hearing about the damn emails," Sanders said. "Enough of the emails. Let's talk about the real issues facing the United States of America." Hide Caption 36 of 43 Photos: Hillary Clinton's life in the spotlight Clinton is reflected in a teleprompter during a campaign rally in Alexandria, Virginia, in October 2015. Hide Caption 37 of 43 Photos: Hillary Clinton's life in the spotlight Clinton walks on her stage with her family after winning the New York primary in April. Hide Caption 38 of 43 Photos: Hillary Clinton's life in the spotlight After Clinton became the Democratic Party's presumptive nominee, this photo was posted to her official Twitter account. "To every little girl who dreams big: Yes, you can be anything you want -- even president," Clinton said. "Tonight is for you." Hide Caption 39 of 43 Photos: Hillary Clinton's life in the spotlight Obama hugs Clinton after he gave a speech at the Democratic National Convention in Philadelphia. The president said Clinton was ready to be commander in chief. "For four years, I had a front-row seat to her intelligence, her judgment and her discipline," he said, referring to her stint as his secretary of state. Hide Caption 40 of 43 Photos: Hillary Clinton's life in the spotlight Clinton arrives at a 9/11 commemoration ceremony in New York on September 11. Clinton, who was diagnosed with pneumonia two days before, left early after feeling ill. A video appeared to show her stumble as Secret Service agents helped her into a van. Hide Caption 41 of 43 Photos: Hillary Clinton's life in the spotlight Clinton addresses a campaign rally in Cleveland on November 6, two days before Election Day. She went on to lose Ohio -- and the election -- to her Republican opponent, Donald Trump. Hide Caption 42 of 43 Photos: Hillary Clinton's life in the spotlight After conceding the presidency to Trump in a phone call earlier, Clinton addresses supporters and campaign workers in New York on Wednesday, November 9. Her defeat marked a stunning end to a campaign that appeared poised to make her the first woman elected US president. Hide Caption 43 of 43

The GOP establishment has yet to fully rally around the billionaire New York businessman, who trails Clinton 46% to 40% in the latest CNN Poll of Polls and has struggled to raise money in comparison to the Clinton and Democratic juggernaut.

The revelations of the email server as part of the House's Benghazi probe have also resulted in lawsuits filed in Freedom of Information Act cases by the conservative Judicial Watch and other groups.

One such lawsuit saw Clinton's top aide, Huma Abedin, deposed this week, along with other State Department staffers.

A State Department Inspector General report released in late May said Clinton failed to follow rules or inform key staff about the server.