WESTERVILLE, Ohio — Hunter Biden, former Vice President Joseph R. Biden Jr.’s son, acknowledged in an interview to be broadcast on Tuesday that he probably would not have been named to the board of a foreign company if his last name weren’t Biden, but he rejected suggestions by President Trump that he and his father had engaged in wrongdoing.
“Did I make a mistake? Maybe in the grand scheme of things,” Mr. Biden said in an interview with ABC News, which published excerpts from it on Tuesday morning. “But did I make a mistake based on some ethical lapse? Absolutely not.”
“I don’t think there’s a lot of things that would have happened in my life if my last name wasn’t Biden,” Mr. Biden told Amy Robach of ABC.
Mr. Trump has seized on the younger Mr. Biden’s work in Ukraine and China to launch a series of attacks against the former vice president, a leading Democratic presidential candidate, over the past month. There is no evidence for the president’s claims that Mr. Biden, while in office, improperly intervened to aid his son, but that has not stopped him and other Republicans from raising questions about possible conflicts of interest.
The younger Mr. Biden, who recently resigned from the board of a Chinese investment company, said his service there had become a “distraction, because I have to sit here and answer these questions. That’s why I have committed that I won’t serve on any board or work on any foreign entities when Dad becomes president. That’s the rule I’m going to adhere to.”
Mr. Biden, 49, said he had exercised “poor judgment” by getting involved in a situation that he compared to a “swamp.” But he blamed his father’s opponents, including Mr. Trump, for spreading a “ridiculous conspiracy idea” involving his work.
“I gave a hook to some very unethical people to act in illegal ways to try to do some harm to my father,” he said. “That’s where I made the mistake. So I take full responsibility for that. Did I do anything improper? No, not in any way. Not in any way whatsoever.”
Many Democratic strategists and officials have warned that the issue threatens to become a distraction for the former vice president. Hunter Biden’s interview will be aired just hours before his father is to appear at the fourth presidential primary debate on Tuesday night. There, Mr. Biden will stand at the center of the stage, along with Senator Elizabeth Warren of Massachusetts, who recently surpassed Mr. Biden in several polls.
The scrutiny on Mr. Biden and his family over the past month has injected a degree of risk and uncertainty into his campaign, making it all the more urgent for him to land the kind of consistently fluent, forceful debate performance that has so far eluded him, Democratic operatives and activists said.
A lawyer for Hunter Biden said Sunday in a statement that he planned to leave the board of the Chinese private equity company by the end of October, and that if the elder Mr. Biden were elected president, Hunter Biden would “agree not to serve on boards of, or work on behalf of, foreign-owned companies.”
Mr. Biden had previously served on the board of a Ukrainian gas company, Burisma Holdings, including during a time when his father was running American policy in that country, but he stepped down when the elder Mr. Biden announced his candidacy for the Democratic nomination.
While Mr. Biden said he learned of the statement from his son’s lawyers, the move appeared to be the first acknowledgment that Hunter Biden’s overseas business dealings posed a threat to his father’s campaign.
For his part, the elder Mr. Biden on Sunday forcefully defended his son’s integrity and vehemently denied that there were conflicts of interest at play.
Instead, he took several barely veiled swipes at members of the Trump family, promising: “No one in my family will have an office in the White House, will sit in on meetings as if they’re a cabinet member, will in fact have any business relationship with anyone that relates to a foreign corporation or a foreign country.”
On Monday morning, Mr. Biden’s campaign released a plan centered on promoting ethics in government. His campaign and his allies have said that Mr. Biden would both push back forcefully against Mr. Trump and continue to discuss policy matters, like health care, on the debate stage and on the campaign trail.
Katie Glueck reported from Westerville, Ohio, and Stephanie Saul from New York.