WASHINGTON (AP) — Utah Sen. Mitt Romney says he will support a subpoena to interview a witness and obtain records related to Burisma, the gas company in Ukraine linked to former Vice President Joe Biden’s son. The push comes as Biden has emerged as a front-runner to challenge President Donald Trump in November’s election.

Romney, the lone Republican who voted to convict Trump in last month’s Senate impeachment trial, was in a position to play spoiler on the Homeland panel. The panel’s chairman, Wisconsin Sen. Ron Johnson, plans a vote Wednesday to proceed with an investigation of Hunter Biden’s activities in Ukraine, but will need every Republican vote to issue a subpoena.

There is no evidence of wrongdoing by the Bidens, and Hunter Biden has denied using his influence with his father to aid Burisma. But Republicans coming to Trump’s defense during and after last year’s impeachment trial have encouraged investigations of his activities, questioning whether they created a conflict of interest for Joe Biden as he worked on Ukraine policy in the Obama administration.

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Johnson has said that he will hold a vote to subpoena Andrii Telizhenko, a consultant to a lobbying firm that worked with Burisma, for documents and testimony.

In a letter to Michigan Sen. Gary Peters, the committee’s top Democrat, Johnson said “the American people have a right to know how their government officials conducted official business, whether certain parties received special treatment, and whether any apparent or actual conflict of interest unduly influenced U.S. policy.”

Romney said Thursday that he would prefer investigations to be conducted by “an independent, non-political body.” Asked if the investigations appeared political, he said “the appearance isn’t good.”

But Friday his spokeswoman, Liz Johnson, said Romney had expressed his concerns to Ron Johnson, and that the chairman confirmed that “any interview of the witness would occur in a closed setting without a hearing or public spectacle.”

Romney “will therefore vote to let the chairman proceed to obtain the documents that have been offered,” the statement read.

Johnson insists his committee’s investigation is not political. He points to letters he wrote Peters in February on his intent to pursue the probe, which was before Biden won several states on Super Tuesday and revived his candidacy.

“I see no reason why anybody would object to this,” Johnson said Thursday. “And I didn’t want to publicize this.”

Trump’s efforts to have Ukraine investigate Hunter Biden’s role as a board member for Burisma were at the heart of House Democrats’ impeachment probe last year. He asked Ukrainian President Volodymyr Zelenskiy to investigate the Bidens on a July phone call that was revealed by a whistleblower complaint last fall. The House impeached him in December for pressuring the Ukrainian government while withholding military aid to the country.

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Democrats have denounced Johnson’s Senate investigation as partisan.

“This investigation should not be part of what we’re doing in Homeland Security,” Peters, the Michigan Democrat, said this week. “There are too many other important issues that impact the security of our country, like coronavirus and cyberattacks.”

The subpoena is part of a larger committee investigation into Burisma. Johnson and Senate Finance Committee Chairman Chuck Grassley last year asked the State Department for all documents related to Hunter Biden, Burisma and other people and entities related to the companies.