(WASHINGTON) — The Senate Homeland Security and Governmental Affairs Committee is expected to vote Wednesday morning on whether 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.

Sen. Mitt Romney, R-Utah, told ABC News Tuesday he’s unsure how he will vote, citing concerns about the apparent political nature of the probe. Opposition from Romney is enough to table the effort.

“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.

This is not the first time Romney has raised concerns about the potential for over-politicization of the panel’s investigation. The probe 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, however, told ABC News that he is confident he has the votes, a crucial outcome that is expected to keep the chairman on track to produce a report, he says, before Nov. 3.

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.

Democrats have charged that the entire undertaking 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 efforts.

“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.

Johnson and Grassley have repeatedly denied receiving any information from Derkach.

“We flatly reject and deny any claims that we have received, much less are relying on, any materials received from Andriy Derkach – and there is no such evidence to support these false Democrat claims,” they wrote in a press release earlier this month.

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.

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 refuted 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.”

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