In a letter he plans to send to Secretary of State Mike Pompeo on Thursday, Graham said he will request any records of conversations Biden had with then-Ukrainian President Petro Poroshenko in February 2016.

“I want to know if there’s any transcript or readouts of the phone calls between the vice president and the president of the Ukraine in February after the raid on the gas company president’s house,” the South Carolina Republican told Fox News host Sean Hannity on Wednesday.

Shokin was appointed prosecutor general of Ukraine on Feb. 10, 2015, and had taken up the investigation into Zlochevsky, but was accused of slow-walking the effort. Little more than a year later, on March 29, he was removed by Ukraine’s Parliament at Poroshenko’s behest.

Shokin’s fate is now entwined with the House Democrats’ impeachment proceedings.