Leaders of the new left have a tricky 2020 objective: taking down Joe Biden.

The former vice president insists he’s one of them. “I have the most progressive record of anybody running,” he said last week at a Democratic Party dinner in Delaware, his home state, before quickly clarifying that he hadn’t yet decided to run for president.

But to the progressives driving the party toward a younger and ideologically purer end, that wasn’t what screamed out for a correction. Biden, 76, has a long history of Senate votes and public statements and bipartisan friendships at odds with their movement — a movement that is expected to play a significant role in the Democratic primaries.

“A lot of people have a fondness toward Joe Biden because of his time in the Obama White House,” said Maurice Mitchell, national director for the Working Families Party. “That’s quaint and nice. People owe him a fondness. Now this is primetime, and he wants to put his hat in the ring to be the person who has the nuclear codes, the person who is going to transform our country after Trump has brought all this disarray. So there’s going to be a great deal of new scrutiny placed on his record, and there should be.”

Already in the months-long run-up to his anticipated campaign, Biden has expressed regret for supporting anti-crime legislation that disproportionately punished minorities and for his dismissiveness toward Anita Hill’s sexual harassment accusations against Clarence Thomas during Thomas’s Supreme Court confirmation hearings. There also have been reminders of how he opposed school integration 45 years ago and of his eulogy for Strom Thurmond, who rose to political prominence as a segregationist. More recently he found himself on the defensive after calling Vice President Mike Pence, who’s known for pushing anti-gay policies, a “decent guy.”

Biden often tops polls of the Democratic field and would enter the race as the early frontrunner. Mitchell and other liberal activists who spoke to BuzzFeed News are preparing to make sure he peaks on announcement day by emphasizing the parts of Biden’s record they find insufficiently progressive. At the moment, their plans are vague promises and warnings that they will raise objections publicly. It’s less clear how coordinated these efforts might be, or if they’ll have enough money to make much of a dent. And there’s some disagreement over how big of a threat Biden really is.

“I think there’s going to be a lot less air in the room than it looks like for Biden,” said Charles Chamberlain, who chairs Democracy for America, the group that grew out of Howard Dean’s presidential campaign 15 years ago. “The reality is that Biden’s time is passed.”

That kind of confidence worries Sean McElwee, cofounder of the Data for Progress think tank and purveyor of the "Abolish ICE" rallying cry that has electrified many Democrats.

“The problem is that progressives are overestimating how much this will hurt him,” he said. “I see Biden as the Democratic Trump. He has a pretty strong lead in the polls. He’s not really someone who anyone in the party elite is most excited for. Everyone just sort of believes that all this baggage he has will ‘hashtag’ cancel him from the race. Maybe. Possibly. But the governor of Virginia also had a blackface scandal, and no one talks about that anymore.”

McElwee is emerging as one of Biden’s most strident critics on the left: “does joe biden have a long track record of progressive policy? no,” he tweeted this week. “does joe biden spend every day working to atone for decades of enabling racist, sexist and pro-corporate policies? also no.”

A Biden spokesperson declined to comment for this story.

Sen. Chris Coons, a Biden ally who holds his old Senate seat in Delaware, emphasized Biden’s past efforts on climate change and his support for LGBTQ rights in an interview with BuzzFeed News. (Biden and many other Democrats in the 1990s voted for the Defense of Marriage Act, which defined marriage as between a man and a woman. As vice president, Biden famously got out ahead of Obama and to announce his support for marriage equality.)

“If folks want to get into fights over votes he cast 30 and 40 years ago and ignore things that President Trump literally said or did yesterday, and the ways in which Joe Biden is the right person to look forward and pull us into a better future as a country, that’s their prerogative,” said Coons, who plans to endorse Biden if he runs. "But I don’t think that’ll work in the end.”

Even as he asserts that he’s the most progressive 2020 hopeful, Biden does not shy away from his more centrist tendencies. He wasn’t happy about having to walk back the Pence compliment and has at times sounded incredulous over the notion that his relationships with Republicans could be seen as anything other than assets. His allies cite this crossover appeal when arguing that he is the most electable Democrat, the best positioned to beat Trump.

Through his think tank, McElwee plans to conduct a poll that examines whether a Biden-versus-Trump election will turn off “the next generation of voters.” The data, which McElwee said he will share regardless of whether it validates his opinion of Biden, could provide some direction for the progressive groups eager to prevent him from winning the party’s nomination.

Officials at Justice Democrats, a progressive group that played a significant role in 2018’s elections and is closely tied to Rep. Alexandria Ocasio-Cortez, are contemplating 2020 messaging that would shame Democrats seen as too cozy with big business — Biden’s support for and from the financial industry is a likely topic for scrutiny — and with Republicans.

“We’re also going to name the people that are responsible for the mess that we’re in,” said Alexandra Rojas, the group’s executive director. “We definitely want to spread the message that [Biden] represents the centrist wing of the Democratic Party that is radically out of touch.”

Mitchell, whose Working Families Party endorsed Bernie Sanders in the 2016 primaries, said WFP will evaluate all candidates and their records before backing anyone for 2020. He listed several issues he sees as working against Biden, from his opposition to busing as a means of integrating schools in the 1970s to the crime bill and Anita Hill.

“During one of these primary debates, he will be the only candidate who was on the wrong side of school segregation,” Mitchell said. “When he could have intervened for working people, when he could have intervened for women, for people of color, in these cases he chose not to.”

Asked how the WFP would raise these concerns — Paid advertising? Social media? Pushing for coverage from news outlets? In private with the candidates and their staff? — Mitchell replied: “All of the above. We’re going to engage on the staff levels with the candidates, in person, and in public. We believe these issues and this debate needs to be aired publicly.”

Democracy for America’s Chamberlain is similarly harsh on Biden but also suggested that DFA’s messaging would not be explicitly hostile. “I don’t think we’re going to need to do it quite like that,” he said. “We’re going to be running a positive campaign, but one that includes tough questions.”

Chamberlain believes Biden would do well to follow the lead of Sen. Sherrod Brown, who this month decided against a presidential run after visiting the first four caucus and primary states. Brown, otherwise a well-established liberal from Ohio, declined to embrace new left causes like Medicare for All and the Green New Deal — positions that sometimes disappointed the early-state activists he met.

“Sherrod Brown is a very smart, talented person,” Chamberlain said. “He gets it. When he heard a pin drop when he said something like that, he said, ‘This isn’t the year for me.’”

That’s not exactly how Brown framed his decision not to run; he said he’d find more joy fighting for his causes in the Senate. (A popular theory is that Biden scared off Brown by informing him of his imminent candidacy, but Brown and his allies have denied this.) If anything, Brown’s flirtations with a White House bid foreshadowed a way to compete against Biden while subtly emphasizing his problematic votes.

Brown, in an interview days before passing on the 2020 race, reminded BuzzFeed News how he voted against the North American Free Trade Agreement, against DOMA, and against the Iraq War. Biden voted for all three, though Brown said he had no plans to draw such contrasts directly.

“I don’t need to make them,” he said. “I think people will see a long-term progressive commitment from me.”