A number of Democratic presidential candidates, including Sen. Cory Booker and New York City Mayor Bill de Blasio, are calling on former Vice President Joe Biden to apologize for his recent comments about “civility” in Washington, in which he boasted about being able to work with segregationist senators.

“Vice President Biden’s relationships with proud segregationists are not the model for how we make America a safer and more inclusive place for black people, and for everyone,” Booker said in a statement, adding: “Frankly, I’m disappointed that he hasn’t issued an immediate apology for the pain his words are dredging up for many Americans. He should.”

On the eve of Juneteenth, the day celebrating the end of slavery in the United States, Biden invoked two of his former Senate colleagues — Georgia’s Herman Talmadge and Mississippi’s James Eastland, both southern Democrats who opposed desegregation in the 1970s — while making the case that he could bring back an era of consensus building. Biden was elected to the Senate in 1972.

“I was in a caucus with James O. Eastland,” Biden said Tuesday at a fundraiser at the Carlyle Hotel in New York City, according to a press pool report. “He never called me ‘boy,’ he always called me ‘son.’”

Of working with Talmadge, Biden said, “At least there was some civility. We got things done. We didn’t agree on much of anything. We got things done. We got it finished. But today you look at the other side and you’re the enemy. Not the opposition, the enemy. We don’t talk to each other anymore.”

The comments have received widespread backlash. Eastland repeatedly referred to black people as an “inferior race,” and was known as “The Voice of the White South.” Talmadge was a vocal opponent of civil rights legislation and strongly advocated for schools to remain segregated.

Sanders tweeted that he agreed with Booker.

I agree with Cory Booker. This is especially true at a time when the Trump administration is trying to divide us up with its racist appeals. https://t.co/VyVcG6srQM — Bernie Sanders (@BernieSanders) June 19, 2019

Earlier in the day, New York City mayor and 2020 candidate Bill de Blasio blasted Biden on Twitter and posted a photograph of his family, writing that one of the lawmakers Biden cited “thought my multiracial family should be illegal.” De Blasio went so far to say it was “past time for apologies or evolution” from Biden. “He repeatedly demonstrates that he is out of step with the values of the modern Democratic Party,” the mayor tweeted.

It’s 2019 & @JoeBiden is longing for the good old days of “civility” typified by James Eastland. Eastland thought my multiracial family should be illegal & that whites were entitled to “the pursuit of dead n*ggers." (1/2) pic.twitter.com/yoOOkpaTX2 — Bill de Blasio (@BilldeBlasio) June 19, 2019

Sen. Kamala Harris, another 2020 candidate, also commented on Biden’s remarks.

“Yes, it concerns me deeply,” she told a reporter in the Senate. “If those men had their way, I would not be in the United States Senate and on this elevator right now.”

Later, she added, “To coddle the reputations of segregationists is ... misinformed and wrong.”

.@SenKamalaHarris on Biden: “To coddle the reputations of segregationists...is misinformed and wrong.” pic.twitter.com/jpM02p5jiy — Mariam Khan (@MKhan47) June 19, 2019

The Washington Post’s Sean Sullivan asked Sen. Elizabeth Warren about Biden’s comments, and she responded, “I’m not here to criticize other Democrats, but it’s never okay to celebrate segregationists. Never.”

Biden’s adviser Symone Sanders defended the comments on Twitter late in the day on Wednesday, calling the former vice president an ally in the fight for civil rights before pivoting to attack President Donald Trump.

Let's be honest here, a person currently sits in the White House who has ACTUALLY praised white supremacists, refuses to acknowledge the innocence of the #exonerated5 and talks about criminal justice reform, but has yet to allocate ONE PENNY to it in his budget. Meanwhile... — Symone D. Sanders (@SymoneDSanders) June 19, 2019

As Vox’s Andrew Prokop writes, Biden’s comments are part of the former vice president’s well-established approach to politics, one that stresses the working across the aisle and civility.

That said, “the comments fit uncomfortably with a changing Democratic Party and provide ammunition for his more combative challengers ahead of the first Democratic debate next week,” Prokop notes. It would seem that Biden’s rivals aren’t waiting until those debates to denounce his words, and the issue may very well resurface when the candidates face off against each other onstage next week.