Sen. Cory Booker and New York City Mayor Bill de Blasio harshly criticized Democratic frontrunner Joe Biden Wednesday over his comments about working with segregationist lawmakers in the past.

In a marked contrast from the so-far mostly friendly primary, the two candidates took on the former vice president directly after he reminisced about his cordial relationship with Sens. James Eastland and Herman Talmadge when he first joined the Senate.

De Blasio, who is married to a black woman, tweeted a reference to a handbill circulated by Eastland supporters at his rallies which twisted the Declaration of Independence to say that “whites are created with certain rights, among them are life, liberty, and the pursuit of dead n—-rs.”

“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,’” de Blasio wrote on Twitter. “It’s past time for apologies or evolution from @JoeBiden. He repeatedly demonstrates that he is out of step with the values of the modern Democratic Party.”

Booker rebutted Biden’s remark that Eastland “never called me boy” — a demeaning term whites often used to address black men of all ages in the segregation era — by tweeting an iconic image of striking sanitation workers in Memphis carrying signs that said “I am a man.”

“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. “I have to tell Vice President Biden, as someone I respect, that he is wrong for using his relationships with Eastland and Talmadge as examples of how to bring our country together.”

“And 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.”

Several other candidates also spoke out later in the afternoon, including Sen. Bernie Sanders, who said he agreed with Booker’s statement. Sen. Elizabeth Warren said “it’s never OK to celebrate segregationists,” according to CNN, and Sen. Kamala Harris reportedly said Biden’s comments concerned her “deeply.”

“If those men had their way, I wouldn’t be in the United States Senate and on this elevator right now,” Harris said, according to ABC.

Biden’s comments came at an Upper East Side New York fundraiser on Tuesday, where he was recalling his time in the Senate to a crowd of about 100 people.

“I was in a caucus with James O. Eastland,” Biden said, even briefly using a southern accent, according to a pool report. “He never called me boy, he always called me son.”

Biden also addressed Talmadge, who he referred to as “one of the meanest guys I ever knew.”

“You go down the list of all these guys. Well guess what? 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,” he said. “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.”

Both late senators were segregationist Democrats from the South, and today they’re best remembered for their racist legacies: Among other things, Eastland claimed that the Civil Rights Movement was backed by communists, while Talmadge criticized the Supreme Court’s Brown v. Board of Education decision to desegregate schools.

The criticism came on a particularly notable day, as the House held committee hearings on a bill to study reparations for slavery, while many Americans celebrated Juneteenth, a holiday commemorating the emancipation of slaves in the Confederacy. Booker, who introduced a Senate version of the bill, testified at the hearings earlier in the day.

Senior members of the Congressional Black Caucus defended Biden, however, arguing the remarks were taken out of context.

“I worked with Strom Thurmond all my life,” House Majority Whip James Clyburn told Politico, referencing a segregationist senator. “You don’t have to agree with people to work with them.”

Write to Lissandra Villa at lissandra.villa@time.com.