Secretary of Energy Rick Perry reacts during a news conference after the Partnership for Transatlantic Energy Cooperation conference in Vilnius, Lithuania October 7, 2019.Ints Kalnins | ReutersHouse Democrats issued a subpoena to Energy Secretary Rick Perry on Thursday, the latest salvo in the party’s impeachment probe into whether President Donald Trump abused his power through his interactions with the leadership of Ukraine.The subpoena for a variety of Ukraine-related documents was issued by the Democratic chairmen of the House Intelligence, Oversight and Foreign Affairs committees. It provides a deadline of Oct. 18.”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 lawmakers, Reps. Adam Schiff of California, Elijah Cummings of Maryland and Eliot Engel of New York, wrote in a letter to Perry announcing the subpoena. “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,” they wrote. The Department of Energy did not immediately respond to a request for comment. The subpoena marks the next step in the rapidly unfolding impeachment investigation. Democrats have announced nine subpoenas since the inquiry started, according to an NBC News tally. Perry has come into focus for his role encouraging Trump to take the July 25 phone call with Ukraine’s president at the center of the impeachment investigation. Trump used the call to press Ukrainian President Volodymyr Zelensky to investigate Trump’s potential 2020 electoral rival Joe Biden, the former vice president.Democrats are examining whether Trump sought to tie that request to hundreds of millions of dollars in military aid for the country. Trump has denied that there was any such quid pro quo, and said that he was simply urging the country to clean up corruption.Nevertheless, Trump sought to pin the phone call on Perry during a meeting with House Republican lawmakers last week, the news website Axios reported. For its part, Perry’s office confirmed that the former Texas governor encourage Trump to take the call, but told the Associated Press that Perry hoped the purpose of the call would be a discussion of “energy security and economic development.”Before becoming entangled in the swirling impeachment controversy, Perry largely avoided headlines during his tenure at the helm of the Department of Energy, which oversees the nations nuclear program and produces energy-related research. On Monday, he denied reports in Politico and other outlets that he was planning to leave his post at the end of November.It’s unlikely that Perry will cooperate with Democrats’ request. On Tuesday, Pat Cipollone, the White House counsel, sent a letter to Democratic leadership declaring that the impeachment probe was unconstitutional and notifying the lawmakers that the White House did not intend to comply.This is breaking news. Check back for updates.