Although Clinton and her campaign team are wise enough to understand that her vice presidential pick won't create a "game-changing" moment, they also don't want to make any big mistakes. In a campaign where the threat facing Democrats is uncertain and unpredictable, they also will want to make a choice that has the potential to become a tool against the insurgent Republican campaign.
So who are the possible candidates being considered, and what value do they bring to the ticket? The selection will come down to the person who will be a good partner in governance and who will do no harm to the ticket. At the same time, the selection will really depend on what qualities Clinton wants to stress about her campaign.
If Clinton wants to make a pick that will energize her candidacy and excite the millions of voters who came out for Bernie Sanders demanding that the party embrace its progressive ideals, there are four main choices on the table.
Elizabeth Warren: Sen. Warren would clearly be the most energizing pick for Clinton and for the campaign. Selecting Warren would add the kind of star power to the Democratic ticket that would greatly enhance the historic nature of Clinton's candidacy.
Warren would excite for two reasons. First, she is the most commanding figure, other than Bernie Sanders, in the progressive wing of the Democratic Party. Selecting Warren would send a clear signal to Democrats that a Clinton White House will understand the need to address the economic struggles facing so many middle class Americans and the need to impose stronger regulations on financial and business institutions.
Second, in states like Pennsylvania and Ohio, where Trump will make a play for disaffected Democratic voters, Warren could offer a powerful retort and remind these voters that the economic policies of Trump and the GOP don't really match up with the promises he is making about restoring their economic security.
Her negatives are clear. Most important, she will give Trump the opportunity to tag the Democrats as left of center. She doesn't have as much foreign policy experience as Clinton might like in these turbulent times, and Warren has already faced a small controversy by having claimed Native American identity earlier in her career. And if a sexist bias is a big part of this electorate, having two women on the same ticket could give Trump an advantage.
Sherrod Brown: The senator from Ohio is a swing state liberal with political experience who could energize the Democrats. He has a long record of hitting hard on the economic issues that have so concerned Democratic and Republican voters and he could help make sure that Trump does not steal the swing states that will be essential to his victory.
Brown has the ability to play well with blue collar workers who are looking for evidence from either party that they will keep listening to them once the ballots close. He has been one of the strongest voices against free trade agreements, which will help in states like Pennsylvania. Like Warren, he gives Trump the opportunity to paint Democrats as left of center, but without bringing the kind of excitement and energy that Warren adds to the ticket. Harry Reid would not be happy with Brown on the ticket, since that would give Republicans a chance to take back Brown's seat in the Senate.
Tom Perez: The secretary of labor is well liked in the liberal community for his progressive domestic agenda. His record at the Justice Department's civil rights division, fighting on issues like police misconduct, would be a compelling factor for Clinton to do well with African-American voters.
Like Julian Castro, he also would help to ensure that a large number of Hispanic voters come out in November. His problem is that he doesn't have the name-brand value of the other two progressive possibilities, Warren and Brown. He would create a ticket of two former Obama cabinet members, which could be less than thrilling for voters.
Cory Booker: The senator from New Jersey and former Mayor of Newark represents many of the values and outlooks about politics that younger voters have been clamoring for. He has worked hard to address some of the biggest domestic issues that concern millennial and Generation X voters, such as job growth, education and anti-corruption measures.
He has a strong progressive record on issues like criminal justice reform and financial regulation. He would also help bring out the African-American voter, which could prove to be crucial in a number of swing states. He is young, smart and savvy and knows how to work his Twitter account. His ties to Wall Street could be a problem in the current environment, and his support for charter schools might be a source of friction with teachers unions. But picking Booker would surely excite a significant part of the party and bring youthful energy to the campaign trail.
Aiming for Latino and Millennial voters
If Clinton wants a selection that will excite Latino and millennial voters and improve the odds that they will come out on voting day, two names loom larger than any other.
Julian Castro: The U.S. housing secretary and former mayor of San Antonio, only 41 years old, has been talked about frequently as a vice presidential pick who would energize Clinton's campaign by providing a younger political figure. Castro has tackled high-profile issues such as early education and urban planning. Coming from an immigrant family, he could also make sure that the high levels of immigrant voting anticipated for the Clinton ticket come to fruition.
This pocket of the vote could be extremely helpful in states like Florida, Nevada and Colorado, where Latinos are a major part of the population. He could also help with millennial voters who generally have been lukewarm for Clinton. The combination of the two would make a stark contrast with Trump's rhetoric, offering a reminder that Democrats are the party of pluralism, diversity and integration.
His negatives revolve around his lack of experience and the fact that he has not been tested on the national stage. Clinton, who is risk-averse, would take a huge gamble by putting him out front. He would also give Republicans an opportunity to undercut one of her central attributes -- experience and command of policy.
Xavier Becerra: The highest-ranking Latino in Congress would be a bold choice for Clinton. Though he doesn't have the same name recognition as Castro, Becerra has a stellar record on the Hill and is widely respected within the Latino community.
With a Republican candidate who spends much of his time railing against immigrants, this selection would send a strong signal that the Clinton administration would fight for legislation to liberalize immigration. At the same time, given Becerra's resume, he would also confirm the impression that the Democratic ticket is one with governing experience.
Appealing to Trump's base
If Clinton wants to make a pick that will appeal to moderate suburbanites and white male voters -- with whom Trump has been doing well -- while bolstering her case of being the ticket with the most governing experience, there are three choices that are being considered.
Tim Kaine: The senator from Virginia is often described as the safe and "boring" pick for Clinton. He brings to the ticket extensive experience -- having been governor, mayor and senator -- in governance, including foreign policy, and the potential to shore up Clinton's support with centrist Democrats who are worried about the Sanders wing of the Democratic party gaining too much of a voice at the table. Given that Clinton has seen some troubling data regarding the vote of white men in the election, Kaine's addition could help on that front.
His calm demeanor and moderate disposition could be assuring when many voters worry about the temperament of Trump. But there are problems as well. Liberal Democrats would see his selection as a rejection of everything Sanders has been discussing. His ties to Wall Street have already been a concern. His moderate views on abortion can also cause concern.
Given that one of Clinton's challenges has been to create excitement about her candidacy, taking the most "boring" person on the list probably wont help. The recent revelations that he has accepted more than $160,000 in gifts as governor and a political figure in Virginia, all of which were legal under Virginia law, can be a problem in the politics of perception. Clinton understands better than almost anyone that the way things look can matter as much as the technicality of the law. As Trump ramps up his attack on the Clintons as corrupt insiders who make money off of elected positions, this story will provide him more fuel for the attacks.
Tom Vilsack: Like Kaine, he is a white male candidate who could help Clinton with this important group of voters while also bringing an impressive record of governance, leadership and policy to the table. His work as governor of Iowa and as the U.S. secretary of agriculture would add to the long resume of the Democratic ticket.
Like Kaine, Vilsack certainly won't excite voters, and his presence won't calm concerns among liberals about Clinton's long-term commitment to Sanders' issues.
Amy Klobuchar: The Minnesota lawmaker is one of the star figures in the U.S. Senate. The choice is appealing, since Democrats could retain her seat even if she departs. A strong proponent of gun control and family-friendly policies, she could have immense appeal in suburban communities, which will play an important role in most key states.
She could be exciting, adding to an already historic female-headed ticket without being a real flashpoint of controversy. She can help compete in the Midwest where Trump will be making a strong play for voters. One of her flaws, like those of some of the other choices, is that she doesn't have much of a foreign policy record.
What should worry Republicans is the breadth of this field and the number of prominent politicians in the mix. The Democrats have a pretty strong range of candidates to take this job.