Stuart Appelbaum, president of the Retail, Wholesale and Department Store Union, said of the jockeying, “I think it’s a good thing the candidates are campaigning for the position because it gives us a chance to evaluate.”

With the Biden campaign’s vetting process soon to begin, supporters of potential running mates are also getting involved: opposition research that was shelved at the end of the presidential primary is now starting to recirculate in an effort to stealthily drag down prospective vice presidential rivals. Harris, Warren and to a lesser extent Klobuchar — who gained traction relatively late in the campaign — all faced intense scrutiny during the presidential primary. Now, in conversations with reporters, Democrats working to hobble them are reupping old criticisms about their records.

“There are definitely internal and external battles over who’s going to leak the most shit on people,” one Democratic strategist said.

Overt campaigning for the vice presidency has traditionally been frowned upon, weakening those who appear overly eager or insufficiently deferential to the nominee. And with the exception of Abrams — who has said “I would be an excellent running mate” — most top-shelf candidates this year have been guarded about their ambitions, even as they position themselves for a potential selection.

“I just know that, you know, you don’t run for that,” Michigan Gov. Gretchen Whitmer told POLITICO Playbook on Monday — one of many national media appearances Whitmer has made in recent weeks — when asked about the vice presidency, adding, “That is a selection of the top of the ticket, and everyone else should be just busy doing their jobs.”

Harris has said she would “be honored to serve.” When Warren was asked by Rachel Maddow on MSNBC whether she would take the job if Biden offered it, she replied, simply, “Yes.”

The most vocal pressure on Biden is to nominate a black woman. Biden would not be the presumptive nominee if not for his victory in South Carolina, and black voters — particularly black women — are critical to the party’s prospects in the general election.

Harris, who fielded a robust presidential campaign operation but dropped out before the Iowa caucuses, has a large number of former staffers promoting her — many of them with ties to prominent Democrats inside Biden’s orbit. But Abrams and Val Demings, the Florida congresswoman and former Orlando police chief, also have groups of supporters.

“Donors have known about her for a decade,” one strategist said of Demings.

Of all the contenders, Abrams has been the most assertive on the issue of race, telling ABC’s “The View” that it would be a “concern” if Biden did not choose a woman of color.

“As a young black woman, growing up in Mississippi, I learned that if you don't raise your hand, people won't see you, and they won't give you attention," she recently told CNN.

But navigating the Biden campaign’s internal politics may be tricky for Abrams given Atlanta Mayor Keisha Lance Bottoms’ close relationships with Biden brass. Bottoms has long been an Abrams rival, declining to endorse her in the 2018 gubernatorial primary and speaking positively about her opponent, Stacey Evans.

“What a black female candidate would bring is an ability to heighten the enthusiasm … and we’re going to need that in an election that is unlike one that we’ve ever seen before,” said the Rev. Leah Daughtry, a longtime Democratic operative who served as CEO of the 2008 and 2016 Democratic National Convention committees.

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Daughtry, who wants Biden to select a black woman, said the Biden campaign is now confronting “the age-old bet … is it better to place your fortunes on turning out the base of your party, increasing that turnout, or is it better to go after voters you may or may not get.”

Of the Democratic Party’s African American base, Daughtry said, “That’s your sure bet.”

But Biden is also laboring to win over progressive Democrats, and he has a history with Warren.

Before Biden decided not to run for president in 2016, Biden wanted Warren to be his running mate. After they met in August 2015, Warren came away pleasantly surprised despite their past ideological battles, a close ally said during the primary when the two were fighting for the nomination.

Biden also thought Warren would have been a smart choice for Hillary Clinton — and he was not alone.

In a July 2016 memo to Clinton, Philippe Reines, a longtime Clinton confidant, advised that “purely to get you elected, meaning in a perfect world where you’d run with someone but then ditch them for the person you’d prefer as a governing partner, it’s hard to argue that Warren wouldn’t be the most effective running mate. I don’t think it’s close.”

Reines called Warren a “superstar fundraiser” and told Clinton that aside from President Barack Obama, “nobody has Trump’s number like she does. Nobody gets under his skin more. She’s head and shoulders above every other name I’ve seen floated, or out there. I think that would be comforting to you to have such firepower watching your back, and someone who can so easily bait him. That has real strategic value.”

This year, Warren has been casting herself as a governance-first pick, releasing a wave of policy plans and proposed reforms to address the health and economic fallout from the coronavirus.

But she has also been subtly trying to demonstrate her political upside on the ticket. After endorsing Biden, she tried to brandish her small-dollar fundraising machine that raised over $100 million in the primary, deploying her email list on behalf of Biden. It’s not known how much the email raised, but one Democrat familiar with the effort said it impressed at least some Biden staffers.

Several Democratic digital strategists said the strength of the candidate’s social media and email lists may be an underrated factor in the vice presidential search, especially given Biden’s relative weakness in online fundraising.

“This would be maybe the first time in history someone considers grassroots fundraising prowess as a pro for a VP candidate,” said one strategist. “Like, ‘how big of an email list are you bringing us’ is as important as any number of other traditional factors."

One disadvantage for potential candidates who did not run for president is that they have not been subjected to as rigorous a vetting as those who did. While most of the former presidential candidates’ liabilities are already widely known, less certain are the potential weaknesses of contenders who did not run for president, including their ability to perform in debates and on other platforms in a national campaign.

Of the lesser-known commodities, Whitmer is appealing to many Midwestern Democrats because of her forceful response to the coronavirus pandemic in a swing state. But many Democrats also worry about how the electorate would respond to a governor joining a ticket in the midst of the pandemic raging in her state. And if conditions in Michigan worsen, it could become a drag on the campaign.

Biden, who has committed to picking a woman running mate, is expected to announce his vice presidential selection committee by May 1. But the selection itself may not come until July.

Most Democrats familiar with campaign staffs’ discussions about the nomination believe the former vice president will make a decision based largely on personal chemistry and on his confidence in a running mate’s ability to not only help him win — but to govern.

Many Democrats are inclined to give him room to make that decision. Despite calls from Reps. Jim Clyburn (D-S.C.) and John Lewis (D-Ga.) for Biden to pick a black woman as his vice president, some black lawmakers are hesitant to add to the pressure.

“If [Biden] got somebody black or brown, I'm happy, I'm in heaven, but I want to win,” said Rep. Emanuel Cleaver (D-Mo.) “And if Mary Lou, who lives in Pennsylvania, can help him win, I don't care what color she might be.”

“We're going to do ourselves a disservice ... if we fence him in,” Cleaver said. “I don't want to be a part of the fencing-in group.”

