And Elizabeth Warren, the darling of the progressive left, leads the list of liberal VP picks. Putting Warren on the ticket could help unify a Democratic Party thrown into turmoil by a progressive insurgence.
And she's been able to hit the presumptive GOP nominee in a way that none of his other opponents have been able to during the entire primary season. While on "The Late Show with Stephen Colbert," Warren said of Trump: "He is not a business success — he is a business loser."
See Clinton's potential running mates:
Hillary Clinton potential running mates, VPs
The drawbacks of a Clinton-Warren ticket
The junior Democratic Senator from the swing state of Virginia could be a strategic selection for Hillary. Kaine also served as the governor of Virginia from 2006- 2010.
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The current U.S. Senator from Massachusetts is popular among progressive Democrats, and some even tried to draft her to run for president herself in 2016.
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Insiders believe that the senior U.S. Senator from Ohio could help Clinton increase her popularity with working-class voters, a group she has yet to win in a big way so far in primary contests.
(Photo By Bill Clark/CQ Roll Call)
The U.S. Senator from New Jersey is both youthful and charismatic and would add racial diversity to a Clinton ticket.
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The current U.S. Secretary of Labor is considered a sleeper pick by many Democrats because he is not well known outside of D.C., but some believe his strength and popularity among union workers and other progressive groups could be an asset to Clinton's ticket.
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The Independent from Vermont has become Hillary Clinton's primary rival for the Democratic nomination, garnering a surprising amount of support. Bringing Sanders onto the ticket could help to unite both sets of supporters who have been split in Democratic primaries.
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A former 2016 rival of Hillary Clinton, and former Maryland governor, Martin O’Malley could help bring some executive experience, along with a slight youthful boost to the ticket.
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The Secretary of Agriculture since 2009, Tom Vilsack also served as the governor of Iowa from 1999 to 2007. Vilsack could bring some governing experience along with swing state influence.
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Evan Bayh could bring a more right leaning brand of politics to the ticket. Bayh previously served as the junior U.S. Senator from Indiana from 1999 to 2011, and also as the 46th Governor of Indiana from 1989 to 1997.
While the likelihood of him agreeing to take on the veep job again might be low, Biden's popularity among Democrats would likely boost Clinton's chances.
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Hillary's husband is technically allowed to serve in the job, and some legal experts even think he'd be able to take office if necessary. Unfortunately for the diehard Clinton supporters, a Clinton-Clinton ticket will probably be a dream that never comes true.
(Photo By Bill Clark/CQ Roll Call)
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But a Clinton-Warren ticket doesn't come without its downsides.
First of all, it complicates the Democrats' ability to flip the Senate. If Clinton were to win, Warren would leave a vacancy that would be filled, not by an election, but by Massachusetts Republican Gov. Charlie Baker.
And as a senator, Warren has been able to help shift the Democratic Party further left with a populist message that resonates with the most liberal faction of the party.
That's not something she'd be able to focus much time on as Clinton's vice president.
But the most important reason is chemistry. A running mate could be chosen for a few different reasons, ranging from helping win support from a certain demographic to guaranteeing a win in a swing state. But they shouldn't complicate the campaign.
"The credit card companies have been giving money and they have influence. She has taken money from the groups and, more to the point, she worries about them as a constituency," Warren told Bill Moyers in 2004.
Clips of Warren attacking Clinton like this would be easy to find on the internet. And the GOP would jump at the chance to use the words of Clinton's running mate against her. Airing footage of Warren attacking Clinton's judgment would be effective in helping to paint the candidate as untrustworthy.
But if Warren could help Clinton get elected, maybe the bruises they take on the way to the White House would be worth it.