A left-wing advocacy group released a survey in April demonstrating that black voters could cost Joe Biden the nomination — once they are familiar with his record.

Data for Progress's memo on "Joe Biden's Electability" tests the assumption that the former vice president is the Democrats' best chance for winning back the White House in 2020. The group surveyed 1,309 voters on their opinions of Biden before and after reading a number of statements critical of his record as vice president and senator.

Black voters who grew familiar with things such as Biden's opposition to integrating Delaware's public schools and initial support for the Iraq War became less likely to support him in a presidential election.

"These statements cause about five percent of black voters to move away from Biden, representing an 8 percent loss among black voters overall," the study's author Sean McElwee writes.

[ Related: Biden praised segregationist Strom Thurmond as 'closest friend,' who believed in 'heterogenous, diverse society']

Before learning about Biden's record, "61 percent of black voters reported they would support Biden, 15 percent said they would support Donald Trump, 17 percent said they would hold out for someone else, and 7 percent said they would not vote," writes McElwee.

When the study's participants were read statements from Biden's past, his support dropped to 56%, while 22% of blacks said they would "hold out for someone else" and 8% said they would not vote entirely.

Data for Progress concluded that such a shift among black voters and other groups "was enough to flip Biden, from Biden narrowly defeating Trump to Trump safely beating Biden."

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"Considering how much worse things will be in the general election, this should give us pause about Biden’s current strong reputation. That reputation is not necessarily as resilient to the vicissitudes of campaigning as it needs to be in order to defeat Trump in 2020," the study reads.

An 8% loss in black support could significantly damage Biden's chances not only in the Democratic primary, but in a general election. In 2016, Hillary Clinton earned 88% of the black vote, while Trump only won 8%.

Those Clinton numbers were already 5% lower than Barack Obama's in 2012, and Clinton lacked the racial baggage of Biden.

In 1975, Biden argued in favor of black segregation, calling the "concept of busing ... a rejection of the whole movement of black pride." In 1988, Biden spoke of his close relationship with pro-segregationist Sen. Strom Thurmond.

“I get along with Strom Thurmond because I respect him,” Biden said. “Because Strom Thurmond believes deeply in what he does, and he is a consummate legislator. He understands that this country is made up of 240 million people, the most heterogenous, diverse society in the world, and every point of view has to be accommodated."



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