The chairmen of the House Intelligence, Oversight and Foreign Affairs committees subpoenaed Energy Secretary Rick Perry on Thursday, demanding records about his interactions with Ukrainian officials, including the president, a central figure in their impeachment inquiry of President Donald Trump.

In a letter, Intelligence Chairman Adam B. Schiff, Oversight and Reform Chairman Elijah E. Cummings and Foreign Affairs Chairman Eliot L. Engel requested Perry turn over files about his knowledge of a July 25 call between Trump and Ukrainian President Volodomyr Zelenskiy and his activities in and business connections to Ukraine, including with a state-run natural gas company, Naftogaz.

Representatives of the Energy Department did not immediately reply to a request for comment. Perry is traveling in Iceland.

Perry said Monday he “absolutely” told Trump to call Zelenskiy but said he suggested they discuss energy issues. “I asked the president multiple times, ‘Mr. President, we think it is in the United States’ and in Ukraine’s best interest that you and the president of Ukraine have conversations, that you discuss the options that are there,’” Perry said in Lithuania.

As House Democrats expand their impeachment inquiry, Perry has repeatedly emerged as a central figure.

New Jersey Sen. Robert Menendez, ranking Democrat on the Senate Foreign Relations Committee, asked Perry Oct. 1 about the trip he led to Ukraine on May 20, when he attended Zelenskiy’s inauguration. And on Friday, House Democrats requested Vice President Mike Pence supply records about Ukraine and the administration, including files from Perry and the Energy Department.

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The core of the Democrats’ inquiry appears to rest on that July 25 call in which Trump pressured Zelenskiy to investigate former Vice President Joe Biden, a potential 2020 opponent, in exchange for U.S. military aid.

“Recently, public reports have raised questions about any role you may have played in conveying or reinforcing the President’s stark message to the Ukrainian President,” the letter states.

“These reports have also raised significant questions about your efforts to press Ukrainian officials to change the management structure at a Ukrainian state-owned energy company to benefit individuals involved with Rudy Giuliani’s push to get Ukrainian officials to interfere in our 2020 election,” it continues, referencing Trump’s private lawyer.

Engel, Schiff and Cummings demanded records from February 2019 until the present, including recordings, transcripts and notes from contacts between Trump and Ukrainian officials. They gave Perry until Oct. 18 to comply.

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Perry met at least twice with Naftogaz officials: once at DOE headquarters in Washington on April 19, 2017, and again on May 20 this year.

Naftogaz CEO Andriy Kobolyev met Perry in that first meeting, and he was present at the second, along with Wisconsin Republican Sen. Ron Johnson and former U.S. special envoy Kurt Volker.