Senate Judiciary Committee Chairman Lindsey Graham, R-S.C., requested all documents relating to contacts in 2016 between Obama administration officials, including Vice President Joe Biden, and Ukrainian President Petro Poroshenko.

In his letter to current Secretary of State Mike Pompeo, Graham also asked for documents involving Biden’s son, Hunter, who then was a board member of the Ukrainian energy company Burisma Holdings.

Graham noted that Ukrainian authorities, led by Prosecutor General Viktor Shokin, seized property owned by Burisma’s founder, Mykola Zlochevksy, in a February 2016 raid.

Two days later, Hunter Biden began “following” Obama Deputy Secretary of State Tony Blinken, a longtime adviser to his father, on Twitter, “indicating that the two may have initiated conversations regarding Prosecutor General Shokin’s investigation into Burisma.”

Graham noted that Hunter Biden was on Burisma’s board at the time.

The senator also cited news reports saying that Vice President Biden held telephone conversations with President Poroshenko “regarding previous demands to dismiss Prosecutor General Shokin for alleged corruption.”

The pair also talked March 22, 2016, “just seven days” before Shokin was “removed from office,” he said.

Graham told Pompeo that he was seeking the documents, including any involving Secretary of State John Kerry, to “assist in answering questions regarding allegations that Vice President Biden played a role in the termination of Prosecutor General Shokin in an effort to end the investigation of the company employing his son.”