Joe Biden compared President Trump to the kind of bully that he would “smack” in the mouth as a child during an interview broadcast Friday in which the former vice president sought to dispel concerns about his shaky first Democratic debate performance.

Appearing on CNN, Biden was pressed about his ability to stand up to Trump following a debate last week in which Sen. Kamala D. Harris (D-Calif.) aggressively questioned Biden’s opposition to federally mandated busing in the 1970s, appearing to catch him off guard.

“The idea that I’d be intimidated by Donald Trump — he’s the bully that I knew my whole life,” Biden said. “He’s the bully that I’ve always stood up to. He’s the bully that used to make fun when I was a kid that I stutter, and I’d smack him in the mouth.”

During the interview with CNN’s Chris Cuomo, which took place Thursday in Iowa, Biden acknowledged that he wasn’t prepared for Harris’s attack.

“I was prepared for them to come after me, but I wasn’t prepared for the person coming at me the way she came at me,” Biden said, adding that he felt he and Harris knew each other well and that she also knew his late son, Beau Biden.

Biden continued to stress, as he has in recent days, that he was not opposed to all forms of busing, including voluntary busing and busing ordered by courts to address discrimination. What he opposed was busing mandated by the federal government in an attempt to make all schools “balanced across the board,” said Biden, who also sought to defend his record more broadly on civil rights.

Biden said his position on busing had been “taken out of context” by Harris and that the two of them hold roughly the same position about its use in the present. During a campaign stop in Iowa this week, Harris said busing is “a tool among many that should be considered.”

Biden also argued that “busing did not work.”

“You had overwhelming response from the African American community in my state,” Biden said of Delaware. “They did not support it.”

Biden declined to answer a question about whether he would still consider Harris to be his running mate if he wins the Democratic nomination, calling it “presumptuous.”

“I don’t even have the nomination,” Biden said. “I’m not going to comment on any individual.”

He said it would be “great” to have a woman as the Democratic vice presidential candidate or as the presidential candidate if he is not the party’s nominee.

Biden also suggested that the Democratic field should be focused on more current issues than busing.

“I get all this information about other people’s past and what they’ve done and not done. And, you know, I am just not going to go there,” Biden said. “I mean, we should be debating what we do from here.”

Biden sought to distance himself from some of the more liberal policies being offered by fellow Democrats, including a single-payer “Medicare-for-all” health-care system and large tax increases on top earners.

When Cuomo asked him about such “advanced” ideas, Biden disputed the characterization.

“I wouldn’t call them advanced,” he said, adding that it was “mainstream Democrats” who prevailed in the general election in last year’s midterm elections.

He called Rep. Alexandria Ocasio-Cortez (D-N.Y.), a freshman lawmaker who has championed liberal ideas on health care, taxes and the environment, “a brilliant, bright woman.”

“But she won a primary,” Biden said, referring to her victory in a heavily Democratic district in which the Democratic nominee was all but ensured to win the general election.

“In the general election fights, who won?” Biden said. “Mainstream Democrats who are very progressive on social issues and very strong on education and health care.”

Describing the Democratic Party, Biden said: “Look, it’s center left, that’s where I am. Where it’s not is way left.”

Biden also elaborated on a moment in last week’s debate when he and the other nine Democrats onstage raised their hands when asked if undocumented immigrants should have government-subsidized health care.

“I think undocumented people need to have a means by which they can be covered when they’re sick,” Biden said. “That’s what I think we should be doing, by building more clinics around the country, not just for undocumented but for other people. When they’re ill, when they’re sick, it’s just common decency.”

Cuomo pointed out that the idea is unpopular, which Biden acknowledged.

“In an emergency, they should have health care,” he said. “Everybody should. Anybody here in the country. How do you say, ‘You’re undocumented, I’m going to let you die, man?’ ”

While he doesn’t favor a “Medicare-for-all” health-care system, Biden said he supports giving people the option to buy into Medicare.

“But if they like their employer-based insurance, which a lot of unions broke their neck to get, a lot of people like theirs, they shouldn’t have to give it up,” Biden said.

Addressing concerns about his ability to take on Trump, Biden said he has been accused of being “too aggressive.”

“I’d beat him by just pointing out who I am and who he is and what we’re for and what he’s against,” Biden added. “This guy’s a divider in chief.”

During the interview, Biden faulted Trump on several foreign policy issues, including relations with North Korea and China.

Biden suggested Trump had elevated the status of North Korea leader Kim Jong Un without achieving any meaningful concessions toward his nation’s denuclearization.

“Look, you want to talk, you want to deal with us, you want sanctions lifted. Show me something ahead of time,” Biden said.

He also faulted Trump for the trade war with China, calling it “ludicrous,” and suggested Trump was allowing China to pull away from the United States in development of technology.

“While he’s tweeting, China’s going to own the 5G market,” Biden said.

He also predicted that the United States would withdraw from NATO if Trump is elected to a second term.