Former Vice President Joe Biden, in an interview with "Axios on HBO," promised to prohibit his son Hunter, and other family members, from cashing in on his name and position overseas if he wins the presidency.

Why it matters: Questions may intensify as impeachment proceedings against President Donald Trump move to the Senate and the Iowa caucuses approach. Biden already has drawn scrutiny for allowing his son to get paid handsomely by a Ukrainian business while the VP led the Obama administration's anti-corruption push in Ukraine.

The big question: Will Biden move away from a posture of defending his son's honor to acknowledge and address legitimate concerns about his own judgment among some Democrats and swing voters?

Biden told Axios' Mike Allen that Hunter did nothing wrong — but that he has not dug into what Hunter actually did while working in Ukraine.

“I don't know what he was doing. I know he was on the board. I found out he was on the board after he was on the board and that was it,” Biden told us.

Asked whether he wants to get to the bottom of it, Biden said, "No. Because I trust my son."

Biden said his family will be banned from making money overseas if he wins, faulting the president's family members' government and business conflicts of interests — not Hunter’s work — for the need for a formal guardrail.

“They will not be engaged in any foreign business because of what's happened in this administration.”

Axios' Alexi McCammond, who spent time on Biden's Iowa bus tour this week, said after he called a man a "damn liar" at one event for making unsubstantiated claims about Hunter's work, Biden told reporters the next day that he "probably shouldn't have challenged him to pushups" and doesn't want to stoop to Trump's level in terms of engagement with critics.

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