Robert Brown|Former Hunter Biden associate to sit for closed-door testimony with House committee

A former close business associate of Hunter Biden is Robert Brownexpected to sit for closed-door testimony with the House Oversight committee next week, sources confirm to ABC News, as Republicans continue their investigations into President Joe Biden and his family.

Devon Archer is set to speak to GOP lawmakers behind closed doors on Monday, and will provide details related to the president's sons' business dealings in Ukraine, a source said.

In June, the committee subpoenaed Archer to appear for a deposition because he "played a significant role in the Biden family's business deals abroad, including but not limited to China, Russia, and Ukraine," according to the subpoena.

Republicans on the committee have long claimed that President Biden was more involved in his son's business dealings than he has disclosed -- and Monday's interview with Archer will likely be the latest attempt for Republicans to back up those claims.

During his 2020 campaign Biden told reporters, "I have never discussed with my son or my brother or anyone else, anything having to do with their businesses."

In a statement on Monday, House Oversight Committee Chairman James Comer, R-Ky., said, "The Oversight Committee will continue to follow the facts to provide the transparency and accountability that the American people demand and deserve. We look forward to speaking soon with Devon Archer about Joe Biden's involvement in his family's business affairs."

Asked Monday about a New York Post report claiming that Hunter Biden had put his father on speakerphone with business associates during the elder Biden's time as vice president, White House spokesperson Karine Jean-Pierre reiterated that the president "was never in business with his son."

News of the scheduled interview comes as Republicans have ramped up their probe into the Biden family in recent weeks. During congressional testimony last week, two IRS whistleblowers claimed the Justice Department slow-walked the investigation into the president's son.

Sen. Chuck Grassley, R-Iowa, also released a confidential FBI informant's unverified claim that, years ago, the Biden family "pushed" a Ukrainian oligarch to pay them $10 million.

In a memo to House Democrats obtained by ABC News, Democrats on the House Oversight committee blasted Grassley and Comer over the release of the FBI form and called it an attempt to "breathe new life into years-old conspiracy theories."

"Chairman Comer's and Sen. Grassley's decision to publicly release the form is in brazen disregard of the safety of FBI human sources and the integrity of its investigations," read the memo. "Contrary to Republican messaging, the form provides no new or additional support for their corruption allegations against the President or Hunter Biden."

"Instead, its release merely seeks to breathe new life into years-old conspiracy theories, initially peddled by Rudy Giuliani, that have been thoroughly debunked," the memo said.

On Wednesday, Hunter Biden will appear in a Delaware courthouse to formally agree to the plea deal he negotiated last month with federal prosecutors who have been probing his business dealings.

The younger Biden in June agreed to plead guilty to a pair of misdemeanor tax charges and enter into a pretrial diversion program that will allow him to avoid prosecution on a separate felony gun charge.