House Democrats on Friday issued a subpoena to Secretary of State Mike Pompeo, as they investigate whether he helped Senate Republicans advance alleged conspiracy theories about presumptive Democratic nominee Joe Biden.

“Secretary Pompeo has turned the State Department into an arm of the Trump campaign and he’s not even trying to disguise it,” House Foreign Affairs Committee Chairman Eliot Engel said in a statement.

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The committee said the subpoena demands all records related to Biden and Ukrainian energy company Burisma Holdings that the State Department has produced to the Senate Committees on Finance and Homeland Security and Governmental Affairs -- which are controlled by Republicans.

“After trying to stonewall virtually every oversight effort by the Foreign Affairs Committee in the last two years, Mr. Pompeo is more than happy to help Senate Republicans advance their conspiracy theories about the Bidens,” he said. "I want to see the full record of what the department has sent to the Senate and I want the American people to see it too.”

Burisma Holdings was at the center of impeachment proceedings against President Trump, after he pressed Ukrainian President Volodymyr Zelensky during a phone call to look into the Biden family’s dealings in Ukraine. Biden’s son, Hunter, held a lucrative position on the board of Burisma Holdings.

The Obama administration had pushed for a prosecutor who has investigated Burisma, Viktor Shokin, to be fired. Shokin was removed in April 2016 and the case was closed by the prosecutor who replaced him. Biden once 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 was rather tied to the administration’s concerns of corruption in Ukraine. At the time, Biden was running U.S.-Ukraine policy and anti-corruption campaigns.

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The committee alleged that while the State Department has handed over 16,000 of pages of records to the Senate committees, it has refused Engel’s request to provide his office with duplicates.

It requests records from the department by Aug. 7. The State Department did not immediately respond to a request for comment from Fox News.

Fox News' Brooke Singman contributed to this report.