Witnesses in Tuesday’s Trump impeachment hearing both testified that Hunter Biden’s role on the board of Ukrainian natural gas firm Burisma Holdings raised concerns of a potential appearance of a conflict of interest, following a line of intense questioning by GOP Rep. Elise Stefanik.

Stefanik, R-N.Y., grilled both Lt. Col. Alexander Vindman and aide to Vice President Pence Jennifer Williams about allegations of corruption against the company where Biden held a lucrative role on the board while his father, former Vice President Joe Biden, was leading Ukraine policy and anti-corruption efforts there for the Obama administration.

IMPEACHMENT WITNESS URGED BURISMA PROBE, TESTIFIES TO CONCERN OF HUNTER BIDEN 'CONFLICT'

“Every witness who has testified and has been asked this has answered yes,” Stefanik said. “Do you agree that Hunter Biden, on the board of Burisma, has the potential for the appearance of a conflict of interest?”

Vindman replied: “Certainly, the potential, yes.”

Stefanik asked Williams the same, to which she responded: “Yes.”

The Biden family's actions in Ukraine, along with a separate issue connected to 2016 election interference, were at the core of what President Trump wanted investigated out of Kiev. Trump's now-famous July phone call – in which he pressured Ukrainian President Volodymyr Zelensky to launch the investigations – prompted a whistleblower complaint and, in turn, the impeachment inquiry in the House. The president’s request came after millions in U.S. military aid to Ukraine had been frozen, which Democrats and some witnesses have cited as a quid pro quo arrangement.

State Department official George Kent, who testified last week in the first public impeachment hearing held by the House Intelligence Committee, said that he raised concerns with the former vice president's office in 2015 that Hunter Biden’s role on the board of Burisma could present “the possibility of the perception of a conflict of interest.”

Kent also told congressional investigators last month during his closed-door deposition that he had repeatedly raised concerns with the Obama administration about Burisma, and also discussed the administration’s efforts to remove Ukrainian prosecutor Viktor Shokin from his post. At the time, Shokin was investigating the firm's founder.

Shokin was fired in April 2016 and the case was closed by the prosecutor who replaced him, Yuriy Lutsenko. Joe Biden once famously boasted on camera that when he was vice president he successfully pressured Ukraine to fire Shokin.

Biden allies, though, maintain that his intervention had nothing to do with his son, but rather was tied to corruption concerns.

“Are you aware that in 2014, during the Obama administration, the first anti-corruption investigation partnered between the U.S., the U.K., and Ukraine was into the owner of the company Burisma?” Stefanik asked during Tuesday’s hearing.

VINDMAN DOWNPLAYS MISSING BURISMA REFERENCE IN TRUMP CALL SUMMARY: 'NOT A SIGNIFICANT OMISSION'

“I am aware of it now,” Vindman replied.

Stefanik went on to remind Vindman that he testified behind closed doors that he was aware of “questionable business dealings” by Burisma and that it was “part of its track record.”

“That’s correct,” he said.

“You also testified that regarding Burisma, money laundering, tax evasion comports with your understanding of how business is done in the Ukraine,” she added.

“I’m not aware of specific incidents, but my understanding is it would not be out of the realm of the possible for Burisma,” Vindman said.

Stefanik continued pressing Vindman over Burisma, calling it a “corrupt company,” noting that constituents have concerns regarding the company and the younger Biden’s role there, and added that “the Obama administration State Department was also concerned.”

“And yet, Adam Schiff refused to allow this committee to call Hunter Biden, despite our requests,” Stefanik said.

Earlier this month, Republicans on the committee submitted a proposed witness list for the open phase of the impeachment hearings to House Intelligence Committee Chairman Adam Schiff, D-Calif., which included Hunter Biden, his former business partner Devon Archer, the Ukraine whistleblower and others.

At this point, Schiff has denied a number of GOP proposed witnesses, which he has the right to do under the rules governing the impeachment inquiry.