Washington (CNN) Hillary Clinton said Friday that while she will do her "best" to answer the House Select Committee on Benghazi's questions in her testimony next week on Capitol Hill, she doesn't have very much to add and that "conspiracy theories" about the attack have already been debunked.

In the wide-ranging 20-minute interview Friday on CNN's "The Lead with Jake Tapper," Clinton addressed everything from her performance in the first Democratic debate and her top rival for the Democratic nomination Sen. Bernie Sanders to Republican front-runner Donald Trump's "oversize personality" and whether Vice President Joe Biden should jump into the race.

But less than a week before she testifies for the first time before the panel and on the same day as her top aide Huma Abedin testified privately before the committee, Clinton previewed her testimony and girded herself for the tough questioning she is expected to endure by pointing to the committee's political motivations. And it's already clear she is arming herself with the since-repudiated comments of House Majority Leader Kevin McCarthy, who a few weeks ago linked the committee's fate to Clinton's once-slipping poll numbers.

"I think it's pretty clear that whatever they might've thought they were doing, they ended up becoming a partisan arm of the Republican National Committee with an overwhelming focus on trying to -- as they admitted -- drive down my poll numbers," Clinton told Tapper. "I've already testified about Benghazi. I testified to the best of my ability before the Senate and the House. I don't know that I have very much to add."

Clinton also swatted away questions about her use of a private email server during her time as secretary of state and whether she mishandled any classified materials through her email, once again insisting that "nothing that I was sent or that I sent was marked classified."

It's a fine-tuned phrase that she has often repeated in recent weeks as she and her campaign have adjusted their messaging on the controversy swirling around her email use -- messaging that she struggled to keep consistent in the first waves of criticism that plagued her campaign's debut.

Photos: Hillary Clinton's life in the spotlight 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

While it appears none of the emails Clinton sent or received were marked classified, the intelligence community's inspector general has said that some of the emails contained classified information when they were generated -- not just information that was retroactively classified.

Clinton called that "a very strong difference of opinion" and noted that the State Department disagrees with that assertion and explained that various agencies often disagree about what information should or should not be classified.

And addressing her email exchanges with longtime confidant Sidney Blumenthal -- exchanges that have drawn scrutiny and are sure to come up in next week's hearing -- Clinton was quick to insist that nothing he sent her and that she at times forwarded to her aides could be construed as classified "because it came from an outside non-government person."

Clinton, whose use of personal email as secretary of state was permitted under the State Department's rules at the time, said no one at the State Department signed off on her decision to set up a private email server.

The Republican National Committee slammed that answer in a statement Friday and insisted that "what she did was not allowed."

"Hillary Clinton's stunning admission that she unilaterally set up her secret email server that exposed Top Secret material shows she alone is responsible for putting national security at risk," RNC spokesman Michael Short said. "While Hillary Clinton may think she can mislead and laugh off tough questions about her judgment, her growing email scandal personifies why an overwhelming majority of Americans don't trust her."

On Donald Trump

Just as Trump has shown no sign of relenting in his attacks on the Democratic front-runner, Clinton said Friday she will "continue to criticize him for going beyond the bounds of what I think is appropriate for anybody running for president."

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"He has brought his oversize personality and his reality television experience to the highest level of American politics and seems to be getting a very positive response among a large part of the Republican electorate," Clinton said. She praised his daughter Ivanka and noted her friendship with Chelsea Clinton.

While she said Republicans will have to decide if Trump is the right candidate to carry their banner into the general election, she slammed Trump for the "uncalled-for ... insults and the attacks that he's made on immigrants, on women."

On Joe Biden

While Clinton's campaign chairman John Podesta said this week after the debate that "the time has come for a decision" from the vice president on whether or not he will jump into the race, Clinton reiterated that she believes Biden is entitled to his own timeline.

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She said her top strategist was saying that "there does come a point by which a decision needs to be made," but insisted she was not rushing the vice president.

"That's up to Vice President Biden," she said. "Certainly I'm not in any way suggesting or recommending that the vice president accept any timetable other than the one that is clicking inside of him. He has to make this decision."

On her race with Bernie Sanders

Addressing questions about the race for the Democratic presidential nomination, Clinton repeatedly stressed that the differences between her and her Democratic rivals are "nothing like the differences that we all have with the Republicans."

"You could see on that stage in Las Vegas how we are maybe approaching these problems with different solutions, but we're both seeing the pressures that American families are under and the challenges that they're facing," she said. "We're not peddling the same old failed policies of trickle-down economics and let the corporations do what they want and cut taxes on the wealthy."

While Clinton did not hesitate to jab at Sanders, the current runner-up in Democratic polls, during the debate, Clinton slinked from attacking him in the interview Friday, preferring to train her sights on Republicans.

"I think he is raising issues that the electorate -- not just Democrats, everybody needs to be thinking about. He has put forward his plans with passionate intensity and I have put forth mine and just think of the difference between us and the Republicans who have put forward nothing but the same old out of touch, out of date policies," she said of Sanders, a senator from Vermont who is running to Clinton's left.

And while Clinton has taken heat for shifting positions on some issues -- most recently tacking to the left by opposing the Trans-Pacific Partnership trade deal she helped advance as secretary of state -- she reiterated that she has not changed her positions for political reasons.

"I have been the same person. I have the same values, I have the same principles," she said. "There isn't anyone I know in politics who haven't changed a position from time to time."

She said that while she's fought for the same values, she does "look at the evidence and try to figure out what is the best way forward to achieve the goals that I hold."

On guns

Clinton most forcefully criticized Sanders during the debate earlier this week over his positions on gun control -- the one major departure from what has been an overwhelmingly progressive record.

On several occasions, Sanders voted against the Brady bill, which was aimed at imposing tighter gun laws, and has since tacked to the left on guns -- explaining that his views were tied to the fact that he represents a rural state where support for guns is higher.

But Clinton herself spoke differently about guns and gun laws in her 2008 primary against then-Sen. Barack Obama -- one in which she ran to his right as a more centrist alternative.

She said in 2008 that guns are a part of American culture and sent out a mailer criticizing Obama for pushing tougher gun laws.

She said on Friday her comments reflected her years in Arkansas when her husband was governor and has "a lot of experience with and respect for people who own guns, collect guns, use them for hunting, use them for target shooting" and that she respects the Second Amendment.

"But I believe we have gone way too far in being intimidated by the (National Rifle Association), and I have said repeatedly that the majority of Americans and the majority of gun owners support universal background checks," she said. "And for the NRA to take these absolute positions on behalf of the most extreme of their members, and carrying water for the manufacturers and dealers, is just wrong."