The Senate Homeland Security and Governmental Affairs Committee voted Wednesday morning to authorize subpoenas for a number of officials -- including former FBI Deputy Director Andrew McCabe and former Associate Deputy Attorney General Bruce Ohr -- as part of the panel's controversial probe into Burisma, the Ukrainian oil and gas firm for which former Vice President Joe Biden's son, Hunter Biden, once served on the board of directors.
The subpoenas passed out of committee by a vote of 8-6 down party lines.
The committee's investigation is being led by Committee Chairman Ron Johnson, who Democrats have accused of pushing unsubstantiated theories about the Bidens to hurt the former vice president on Election Day.
Johnson's investigation, co-led by Senate Finance Committee Chairman Chuck Grassley, has investigated Hunter Biden's role on the board of Burisma during the time that his father, then the vice president, was leading anti-corruption efforts in Ukraine.
No evidence of wrongdoing on the part of Joe Biden or Hunter Biden has been found. Ethics experts have told ABC News in the past that while there could be an appearance of a conflict of interest, no concrete evidence has been found.
More broadly, the probe also focuses on alleged surveillance abuses during the Obama administration and the so-called "unmasking" of high level officials, including Lt. General Michael Flynn.
During Wednesday's committee hearing, Johnson blamed Democrats for delaying the committees oversight work.
"As I have stated repeatedly the public has a right to know, our investigation is focused on uncovering and revealing the truth but Democrats seem intent at every turn to frustrate and interfere with our oversight efforts," Johnson said.
But Ranking member Gary Peters, D-Mich., blamed his Republican colleagues for focusing on partisan issues while the country continues to struggle fighting the coronavirus.
"Your own public comments, Mr. Chairman, state that your desire to re-investigate these matters demonstrates the alarming partisan nature of this investigation," Peters said.
Democrats have charged that the entire effort to investigate Burisma and the Bidens is predicated on Russian disinformation peddled, at least in part, by Andriy Derkach, a pro-Russian Ukrainian national whom the Department of Treasury sanctioned last week after linking him with disinformation effort.
"You persist in this course of action despite the fact you are knowingly advancing discredited claims that our own Intelligence Community has warned are part of a Russian attack on our democracy," Sen. Gary Peters, the top Democrat on the committee, wrote in a letter to Johnson Monday.
During Wednesday's committee meeting, Johnson called these allegations a "coordinated smear" by Democrats.
"Although neither Senator Grassley nor I ever sought, received or used any information from Mr. Derkach, the media has continued to report otherwise for weeks despite our repeated and unequivocal denials," Johnson said.
At least one Republican has also expressed some skepticism about the nature of the probe as well: Sen. Mitt Romney, R-Utah.
"I made that very clear from the beginning that this has all the appearances of a political endeavor rather than a legitimate government oversight role," Romney said Tuesday. The Senator has raised concerns about this before, though he did vote to advance the probe Wednesday.
Peters, in his letter to Johnson, also pointed to several other investigative efforts which have probed similar allegations and found no wrongdoing on the part of Joe Biden or Hunter Biden.
This is not the first time McCabe and Ohr have been a focus of investigators looking at the underpinnings of the Russia investigation.
The Department of Justice Inspector General found that the information provided to the FBI in early 2016 was "sufficient to predicate" the Russia probe, and the Justice Department has so far not accused McCabe of acting improperly during that investigation. However, the inspector general did find that McCabe lied to investigators about an unrelated leak investigation, ultimately resulting in McCabe's firing from the FBI.
As for Ohr, the Justice Department found that failed to follow the proper chain-of-command when sharing unverified allegations with the FBI related to the Russia investigation, but the inspector general did not find that he acted improperly in relaying the information itself.
Still, Johnson said Monday his committee expects to release a report in a week or two.
"In about a week we're going to learn a whole lot more of Vice President Biden's unfitness for office," Johnson said, according to a report in the Milwaukee Journal Sentinel
Johnson denied questions from Capitol Hill reporters who asked him on Monday if his upcoming report was political in nature.
"No, no, it's about getting the truth out," Johnson said. "My guess would be when people take a look at this they might, might affect them, you know, it probably should, that's just, you know, an obvious fact."