But Biden, the son of former Vice President Joe Biden, conceded that he failed to take into account potential implications for his father's political career.

"Did I make a mistake? Maybe in the grand scheme of things," Hunter Biden said in an ABC News interview that aired on Tuesday. "But did I make a mistake based on some ethical lapse? Absolutely not."

Joe Biden is a front-runner in the 2020 Democratic presidential contest, and the interview with his son aired hours before the fourth Democratic presidential debate.

Hunter Biden said he did not discuss his foreign business dealings with his father. He served on the board of an energy company in Ukraine, a fact he said his father learned from press reports.

The younger Biden was a lawyer at a top Washington law firm with expertise in corporate governance. But he acknowledged on Tuesday that he probably would not have been asked to serve on the board if not for his name.

"I don't think there's a lot of things that would have happened in my life if my last name wasn't Biden," he said.

Trump and his Republican allies have targeted Hunter Biden for his work in Ukraine and China, making baseless claims of corruption.

Trump's July 25 phone call pressuring Ukraine's leader to investigate the Bidens is the focus of a whistleblower complaint that triggered the formal House impeachment inquiry into Trump. Trump has denied wrongdoing.

Hunter Biden recently said he would step down from the board of directors of a Chinese-backed private equity firm because his service had become a "distraction."

"That's why I have committed that I won't serve on any board or work on any foreign entities when Dad becomes president," he said. "That's the rule I'm going to adhere to."

Joe Biden said on Sunday that if he's elected: "No one in my family will have an office in the White House, will sit in meetings as if they're a Cabinet member, will in fact have any business relationships with anyone that relates to a foreign corporation or foreign country."

In 2014, then Vice President Joe Biden was at the forefront of American diplomatic efforts to support Ukraine's fragile democratic government as it sought to fend off Russian aggression and root out corruption. President Barack Obama's White House said there was no conflict with Hunter Biden's work for a Ukrainian gas company because the younger Biden was a private citizen.

Besides Trump's July 25 phone call to Ukraine's leader pressing for investigations, Rudy Giuliani, Trump's personal lawyer, began reaching out to Ukraine's president and his aides to press for a government investigation into the company, Burisma, and Hunter Biden's role.

Hunter Biden blamed his father's political opponents, including Trump, for spreading a "ridiculous conspiracy theory."

"I gave a hook to some very unethical people to act in illegal ways to try to do some harm to my father. That's where I made the mistake," he said. "So I take full responsibility for that. Did I do anything improper? No, not in any way. Not in any way whatsoever."

He added: "What I regret is not taking into account that there would be a Rudy Giuliani and a president of the United States that would be listening to this ridiculous conspiracy idea."

"Being the subject of Donald Trump's ire is a feather in my cap," he said. "It's not something that I go to bed nervous about at night at all. The reason I'm able to do that is because I am absolutely enveloped in love of my family."

In recent weeks, Trump has relentlessly mocked Hunter Biden, to the point that his presidential campaign began selling shirts that say, "Where's Hunter?" highlighting that the former vice president's son had been out of the public spotlight for weeks. At a recent political rally, Trump noted that Hunter Biden had been thrown out of the Navy.

Hunter Biden was discharged from the Navy Reserve in 2014 after failing a drug test and has struggled with alcohol and drug abuse. He told ABC News that, "like every single person that I've ever known, I have fallen and I've gotten up."

"I've done esteemable things and things that are — have been in my life that I regret. Every single one of those things has brought me exactly to where I am right now, which is probably the best place I've ever been in my life. I've gone through my own struggles."