Hunter Biden on Tuesday offered to testify publicly before Congress in response to a subpoena from Republicans investigating nearly every aspect of his business dealings as they pursue an impeachment inquiry into his father, President Joe Biden.

The Democratic president’s son slammed the inquiry as a “fishing expedition” and refused to give closed-door testimony but said he would “answer any pertinent and relevant question” in front of the House Oversight Committee next month, setting up a potential high-stakes face-off.

Rep. James Comer of Kentucky, the chairman of the House Oversight Committee, subpoenaed Hunter Biden in early November in the inquiry’s most aggressive step yet and one that tests the reach of congressional oversight powers. Comer’s office did not immediately respond to a request for comment on Tuesday.

So far, Republicans have failed to uncover evidence directly implicating President Biden in any wrongdoing. But lawmakers insist their evidence paints a troubling picture of “influence peddling” in the Biden family’s business dealings, particularly with clients overseas.

The subpoena demanded Hunter Biden appear before the Oversight Committee for a deposition by mid-December. His uncle James Biden was subpoenaed same day, as well as former business associate Rob Walker.

Hunter Biden’s attorney Abbe Lowell said in Tuesday’s letter that his client had “misgivings about your motives and purpose” but had previously offered to speak with the committee without a response.

“Your empty investigation has gone on too long wasting too many better-used resources. It should come to an end,” Lowell wrote. “From all the individuals you have requested depositions or interviews, all you will learn is that your accusations are baseless. However, the American people should see that for themselves.”

He offered to appear on Dec. 13, the date named in the subpoena, or another day next month.

The subpoenas were bitterly opposed by Democrats, and the White House called for the subpoenas to be withdrawn. Richard Sauber, special counsel to the president, wrote that the subpoenas are “irresponsible” and the product of an overzealous House GOP majority that “weaponized the oversight powers of Congress.”

Congressional Republicans are also probing the Justice Department’s handling of a criminal investigation into Hunter Biden’s business dealings. That long-running case had been expected to end with a plea deal, but it imploded during a July plea hearing.

Hunter Biden is now charged with three firearms felonies related to the 2018 purchase of a gun during a period he has acknowledged being addicted to drugs. No new tax charges have been filed, but prosecutors have indicated they are possible in Washington or California, where he now lives.