Washington (CNN) Virginia Sen. Tim Kaine is emerging as an early favorite to be Hillary Clinton's running mate among major Democratic donors, operatives and congressional Democrats, who argue the Spanish-speaking former governor could be a steady hand in a difficult election environment.

As the party establishment begins to shift its attention to a likely general election matchup against Donald Trump , many Democrats are now arguing that Kaine could help balance out the ticket by helping Clinton with independents in swing states and even expand the political map in the fall with his moderate profile, executive experience and foreign policy background.

And as a politician from a southern state who has endured tough elections, proponents believe he can handle the grind of a high-profile presidential campaign.

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.

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.

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.

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.

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.

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.

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."

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."

Clinton walks on her stage with her family after winning the New York primary in April.

Clinton walks on her stage with her family after winning the New York primary in April.

Clinton is reflected in a teleprompter during a campaign rally in Alexandria, Virginia, in October 2015.

Clinton is reflected in a teleprompter during a campaign rally in Alexandria, Virginia, in October 2015.

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."

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."

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.

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.

Clinton, now running for President again, performs with Jimmy Fallon during a "Tonight Show" skit in September 2015.

Clinton, now running for President again, performs with Jimmy Fallon during a "Tonight Show" skit in September 2015.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

The Clintons pose on the day of Chelsea's wedding to Marc Mezvinsky in July 2010.

The Clintons pose on the day of Chelsea's wedding to Marc Mezvinsky in July 2010.

Clinton, as secretary of state, greets Russian Prime Minister Vladimir Putin during a meeting just outside Moscow in March 2010.

Clinton, as secretary of state, greets Russian Prime Minister Vladimir Putin during a meeting just outside Moscow in March 2010.

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.

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.

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.

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.

Clinton and another presidential hopeful, U.S. Sen. Barack Obama, applaud at the start of a Democratic debate in 2007.

Clinton and another presidential hopeful, U.S. Sen. Barack Obama, applaud at the start of a Democratic debate in 2007.

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.

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.

Clinton announces in February 2000 that she will seek the U.S. Senate seat in New York. She was elected later that year.

Clinton announces in February 2000 that she will seek the U.S. Senate seat in New York. She was elected later that year.

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.

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.

The first family walks with their dog, Buddy, as they leave the White House for a vacation in August 1998.

The first family walks with their dog, Buddy, as they leave the White House for a vacation in August 1998.

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.

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.

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.

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.

The first lady holds up a Grammy Award, which she won for her audiobook "It Takes a Village" in 1997.

The first lady holds up a Grammy Award, which she won for her audiobook "It Takes a Village" in 1997.

The Clintons hug as Bill is sworn in for a second term as President.

The Clintons hug as Bill is sworn in for a second term as President.

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.

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.

Clinton accompanies her husband as he takes the oath of office in January 1993.

Clinton accompanies her husband as he takes the oath of office in January 1993.

During the 1992 presidential campaign, Clinton jokes with her husband's running mate, Al Gore, and Gore's wife, Tipper, aboard a campaign bus.

During the 1992 presidential campaign, Clinton jokes with her husband's running mate, Al Gore, and Gore's wife, Tipper, aboard a campaign bus.

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.

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.

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.

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.

The Clintons celebrate Bill's inauguration in Little Rock, Arkansas, in 1991. He was governor from 1983 to 1992, when he was elected President.

The Clintons celebrate Bill's inauguration in Little Rock, Arkansas, in 1991. He was governor from 1983 to 1992, when he was elected President.

Arkansas' first lady, now using the name Hillary Rodham Clinton, wears her inaugural ball gown in 1985.

Arkansas' first lady, now using the name Hillary Rodham Clinton, wears her inaugural ball gown in 1985.

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.

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.

Rodham was a lawyer on the House Judiciary Committee, whose work led to impeachment charges against President Richard Nixon in 1974.

Rodham was a lawyer on the House Judiciary Committee, whose work led to impeachment charges against President Richard Nixon in 1974.

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.

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.

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.

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.

"I would be 100% enthusiastic about Tim Kaine being our vice presidential candidate," said Peter Buttenwieser, a major Democratic donor and Clinton backer. "Nobody could be better."

How seriously Clinton is considering Kaine is far from certain. But Kaine has been atop Democratic running mate lists before, including in 2008 when Barack Obama's team was vetting the Virginia Democrat for the post before ultimately choosing Joe Biden. Senate Democratic leaders have not taken a position on Kaine as a running mate but would be supportive of his selection, sources said.

In a brief interview last week in the Capitol, Kaine was coy when asked about his interest in the job.

"I'm not on any list that I know of," he told CNN.

Yet two Clinton confidants, who asked not to be named, said Kaine's name has been mentioned frequently as a possible running mate, but said it was too early to know how serious it was.

Kaine, of course, has his drawbacks, too. He voted for fast-track trade authority last year -- something bound to anger the populist, progressive wing of the party led by Sen. Bernie Sanders. He has a more nuanced position on abortion than many liberals. And as a white male, he hardly would be a historic pick the way other prospective vice presidential candidates are.

Moreover, as Clinton has struggled to excite the Democratic base, it's far from clear that Kaine -- a mild-mannered and affable 58-year-old -- would be able to do just that.

Yet as a former chief executive of a swing state, along with his expertise serving on both the Foreign Relations and Armed Services panels, many believe his experience could make him the ideal running mate.

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"It's hard to construct a short list for vice president that he's not on," said Steve Elmendorf, a Democratic lobbyist and Clinton backer.

"He has a business sense and international experience (and) speaks Spanish, which are both pluses," said Glen Fukushima, a Democratic donor who gave $100,000 to Clinton's super PAC last year. "He also has experience as a governor, which could complement Hillary's background."

Other Democrats on Clinton's presumed list of potential picks would be far more historic than Kaine, including women such as Sens. Elizabeth Warren of Massachusetts and Amy Klobuchar of Minnesota, African-American pols like Sen. Cory Booker and former Massachusetts Gov. Deval Patrick, and two Latinos: Labor Secretary Tom Perez and Julian Castro, secretary of housing and urban development.

Two other senators are viewed as potential running mates, including Kaine's Virginia colleague, Mark Warner, and the progressive populist Sherrod Brown of Ohio. Brown told CNN last month that "I don't really want" to be vice president.

What could help Kaine's case is that his state has a Democratic governor, Terry McAuliffe, ensuring that the balance of power in the Senate wouldn't be affected if he became VP since the governor could name an interim replacement. Moreover, as a former head of the Democratic National Committee, Kaine has amassed a network of donors important for a national campaign.

Some of Kaine's allies are pushing his name, including in Virginia.

Rep. Gerry Connolly, who represents a suburban Northern Virginia district outside Washington, told CNN that he is hearing from both voters and party activists about speculation on Kaine as a possible running mate. But he also said the same people are speaking highly of Warner, whom he also praised as a logical choice for Clinton.

"Kaine has a lot going for him -- he's Catholic, from a swing state, successful governor, speaks fluent Spanish, has political chops, was the head of the DNC," Connolly said. "He provides a lot of talent to the ticket and could step in and could certainly be an heir apparent."

A Roman Catholic who taught at a Honduran mission during his law school years, Kaine is personally opposed to abortion but he is supportive of women's right to choose and opposes weakening laws permitting abortion.

But Kaine's allies say he would be able to excite the base by tapping into concerns of income inequality, an issue of prime importance to the base.

"Low-income people, minorities, elderly, people that usually get the short of end of the stick would consider Tim Kaine a friend," said Rep. Bobby Scott, a Democrat who represents Richmond and has known Kaine since he started his political career.