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WASHINGTON — Senate Homeland Security Committee Chairman Ron Johnson has backed down from holding a vote to subpoena an ex-Ukrainian official as part of his investigation of former Vice President Joe Biden and his son Hunter Biden amid concerns from Democrats and some Republicans.

"We will continue to iron out the discrepancies that were raised over the last couple days, and I can't really get into much more than that," Johnson, R-Wis., told reporters.

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Johnson was seeking documents of Andriy Telizhenko, a former Ukrainian Embassy official who consulted for Blue Star Strategies, which represented the Ukrainian energy company Burisma Holdings when Hunter Biden served on the company's board. Telizhenko has been a key figure in pushing the narrative of alleged Obama administration corruption in Ukraine and alleged Ukrainian interference in the 2016 election.

Johnson sent a note to committee members Wednesday shortly before the vote was to have taken place saying that "out of an abundance of caution," he will allow more time for the panel to receive additional briefings before it moves forward.

Johnson told members that he would "instead go straight to the source and compel the same records and an appearance directly from Blue Star Strategies."

It appeared that the subpoena might advance out of the committee when Mitt Romney, R-Utah, said last week that he would support the move after having initially expressed reservations. The sudden change of plans is the latest development in the Senate Republicans' investigation into the Bidens and Burisma, which Democrats have alleged is a politically motivated effort to harm the front-running Democratic presidential candidate.

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Biden campaign spokesman Andrew Bates slammed the investigation Wednesday as "alarming and deeply troubling."

"Senator Johnson is diverting the attention and taxpayer-funded resources of the Senate Homeland Security Committee away from the coronavirus outbreak, which was just designated a global pandemic, to clutch at a conspiracy theory that every fact-checker has debunked," Bates said.