Energy Secretary Rick Perry is expected to announce his resignation next month, Politico reports. Sources told Politico that Perry’s exit was unrelated to the Trump-Ukraine saga that has ensnared the White House and State Department, and said he had been planning his exit for several months. Perry led the U.S. delegation to Ukrainian President Volodymyr Zelensky’s inauguration in May, after Vice President Mike Pence was reportedly ordered not to go by Trump. The energy secretary is also the subject of two congressional subpoenas targeted at Trump’s personal attorney, Rudy Giuliani, who has emerged as a central figure in Trump’s effort to pressure Ukraine into investigating corruption allegations against former Vice President Joe Biden and his son. Deputy Energy Secretary Dan Brouillette is reportedly expected to replace Perry when he exits. The White House has not commented on the matter, and the Department of Energy declined to confirm Perry’s planned exit.