President Biden's brother, James Biden, is testifying Wednesday in a closed-door interview with the House Oversight and Judiciary committees as part of their impeachment probe into the president.

Why it matters: His testimony comes as House Republicans' impeachment effort is on thin ice after one of their key sources of information was charged last week with making up claims.

• James Biden is the first member of the Biden family to testify. Hunter Biden is set to testify on Feb. 28.

Driving the news: James Biden denied that Biden "ever had any involvement or any direct or indirect financial interest" in his businesses, according to his opening statement obtained by Axios.

• "I never asked my brother to take any official action on behalf of me, my business associates, or anyone else," James Biden said.

The big picture: House Republicans, led by Oversight Chair James Comer, subpoenaed James Biden and Hunter Biden in November as part of the impeachment probe.

• It has not yet turned up clear evidence backing GOP allegations that the president benefited from his family's foreign business dealings.

Zoom in: House Republicans cited payments that James Biden made to Biden in 2017 and 2018, including one that Comer claimed is "laundered China money."

• But Democrats have repeatedly refuted the allegations and said that Biden lent the money to James Biden and was repaid.

State of play: James Biden's testimony comes days after the Department of Justice charged an FBI informant, Alexander Smirnov, with making false statements and creating a false and fictitious record.

• Smirnov's indictment was a blow to House Republicans' impeachment push, as his allegations were central to their efforts.
• Smirnov alleged that then-Vice President Biden was implicated in a bribery scheme in Ukraine.

The other side: Democrats and the Biden White House have repeatedly condemned the impeachment push.

• "He is lying and it should be dropped and it's just been an outrageous effort from the beginning," Biden said last week.

Go deeper: House votes to authorize GOP's Biden impeachment inquiry

Axios' Stephen Neukam contributed reporting.

Editor's note: This is a developing story. Please check back for updates.