Former vice president Joe Biden offered a forceful defense of his son Hunter Biden during the opening moments of the fourth Democratic presidential debate on Tuesday, saying that attacks against him were levied by “thugs” President Trump and his personal lawyer Rudy Giuliani.

“My son did nothing wrong,” Biden said on stage. “I did nothing wrong. I carried out the policy of the United States government. That’s what we should be focusing on. My son’s statement speaks for itself.”

Biden added that he was “proud of the judgment” Hunter made to go public in a television interview, before quickly pivoting back on Trump himself. “This president on three occasions has invited foreign governments and heads of government to get engaged to try and alter our elections,” he said. “This is about Trump’s corruption.”

Sen. Cory Booker (D-NJ), when asked a question about a federal jobs guarantee, used several moments of his time to appear to defend Biden.

“I want to say, I am having deja vu all over again,” Booker started, dodging the moderator’s question.

“First of all, because I saw this play in 2016’s election. We are literally using Donald Trump’s lies. And the second issue we cover is elevating a lie and attacking a statesman. That was so offensive. The only person sitting at home that was enjoying that was Donald Trump, seeing we are distracting from his malfeasance and selling-out of his office.”

The elder Biden’s comments came hours after his son gave his first interview about the unfounded allegations regarding his work in China and Ukraine—allegations that have quietly dogged his father’s 2020 campaign.

Speaking to ABC’s Good Morning America about President Trump’s claims of misconduct, which have been bolstered by his personal lawyer Rudy Giuliani, Hunter Biden didn’t go as far to say he would have acted differently in serving on multiple boards of foreign companies. Instead, he stated explicitly that he “did nothing wrong at all,” but conceded that he did not foresee the political toll his prior work would take on his father’s current political fortunes.

“In retrospect, look, I think that it was poor judgment on my part. Is that I think that it was poor judgment because I don't believe now, when I look back on it —I know that there was—did nothing wrong at all,” Hunter Biden said in the Tuesday morning interview with ABC. “However, was it poor judgment to be in the middle of something that is...a swamp in—in—in many ways? Yeah.”

The younger Biden’s television appearance and the elder Biden’s opening comments were not addressed by other candidates on the stage directly, though Sen. Cory Booker (D-N.J.) appeared to try and piggyback on the subject before being cut off by the moderators.

Before the debate, Biden’s deputy campaign manager Kate Bedingfield reiterated that the younger Biden had decided independently to appear on TV the same day as the Democratic debate in Ohio.

“Him sitting down and answering every question is more than you can say for Donald Trump,” she told CNN host Wolf Blitzer.

The Daily Beast reported on Monday that the timing of the interview was seen as perplexing by several rival campaigns, and even by a top Biden surrogate himself, who suggested the move was ill advised.

Before his father launched his presidential campaign in April, Hunter Biden stepped down from the board of a private gas firm in Ukraine. But his work there has been under increased scrutiny by Republicans and the subject of baseless attacks by the Trump White House.

More recently, Trump has turned his focus to the younger Biden’s work in China, though there too Hunter Biden has worked to tie up loose ends. This week, he announced he would step down from the board of the Chinese private equity company on which he served. In addition, his lawyer George Mesires writing that under a hypothetical Biden administration, Hunter Biden would “readily comply with any and all guidelines or standards a President Biden may issue to address purported conflicts of interest, or the appearance of such conflicts, including any restrictions related to overseas business interests.”

Mesires went on to write that, “in any event, Hunter will agree not to serve on boards of, or work on behalf of, foreign owned companies.”

Over the past several weeks, the Biden campaign has denied that any wrongdoing took place, and insisted that unnecessary attention paid to it would only play into Trump’s hands. They’ve even gone so far as to ask that Giuliani not be booked on television networks, pushing the boundaries of traditionally acceptable conduct from a political campaign.

In his ABC interview, Hunter took a moment to turn the attention back to Giuliani, saying he regrets “not taking into account that there would be a Rudy Giuliani and a president of the U.S. that would be listening to this ridiculous conspiracy idea which has again been completely debunked by everyone.”