Joe Biden’s going on the offensive after getting called out by the 2020 Democratic field for bragging about his constructive and civil relationships with white supremacist legislators.

“Apologize for what?” Biden told CNN when he was asked about Sen. Cory Booker’s calling on the former vice president to apologize. “Cory should apologize,” Biden said. “There’s not a racist bone in my body. I’ve been involved in civil rights my whole career.”

Booker, along with several other 2020 challengers, came for Biden on Wednesday after he reminisced about the civility of politicians from the Jim Crow-era South who he worked with in Congress in the '70s. Politics are so partisan now, Biden said, but back then, Democrats and vocal segregationists could get things done together.

“I was in a caucus with James O. Eastland,” said Biden, the current 2020 front-runner. “He never called me ‘boy’; he always called me ‘son.’” Eastland was a staunch segregationist and racist.

Almost immediately, Booker released a statement that he was “disappointed” in Biden and was the first to call on him to apologize. New York City Mayor Bill de Blasio also condemned Biden’s remarks in a tweet that included a photo of his multiracial family.

Some of Biden’s other challenges were less direct. “I’m not here to criticize other Democrats, but it’s never OK to celebrate segregationists. Never,” Sen. Elizabeth Warren said.

Biden’s camp quickly shot back. His adviser, Symone Sanders, tweeted that the flak he was getting was disingenuous and deliberately misconstruing what Biden actually said.

Biden citing a whole career fighting for civil rights is a bit of a stretch. He did support the extension of the Voting Rights Act, sanctions against apartheid South Africa, and the creation of a federal holiday for Martin Luther King, Jr. But in the 1970s, as a freshman senator, Biden fought against busing white children to majority black schools and black children to majority white schools.

“We’ve lost our bearings since the 1954 Brown vs. School Board desegregation case,” he said during a 1975 interview that the Washington Post recently dug up. “To ‘desegregate’ is different than to ‘integrate.’”

Back in 1988, when Biden ran in a failed bid for the presidency, he would occasionally say he marched in the Civil Rights Movement. “When I marched in the civil rights movement, I did not march with a 12-point program,” he said from the stump, according to the New York Times.

When called out on not having actually marched, Biden backtracked defensively: “I find y’all going back and saying, ‘Well, where were you, Senator Biden, at the time?’ — you know, I think it’s bizarre,” he said at a press conference in September of 1987. “Other people marched. I ran for office.”

More recently, Biden also let loose a little casual racism on the campaign trail in 2007 as Barack Obama’s running mate. "I mean, you got the first mainstream African-American who is articulate and bright and clean and a nice-looking guy," Biden said of Obama.

“I didn’t take Senator Biden’s comments personally, but obviously they were historically inaccurate,” Obama responded. Biden apologized for his remarks.

The Democratic presidential field has been careful to avoid overly criticizing each other, but this dust-up is the second time candidates have piled onto Biden in as many weeks.

After Biden, the frontrunner in early polls, said that he still supports the Hyde Amendment, a controversial budget rule that blocks federal funding for abortions except in cases involving rape, incest, or severe health risks to the mother, presidential candidates joined forces to criticize him. A day later, Biden switched his position.