Rep. Trey Gowdy, chairman of the House Select Committee on Benghazi, grilled Hillary Clinton Thursday about her reliance on a divisive political operative for intelligence about Libya.

Clinton’s friendship with Sidney Blumenthal, an aide to her failed 2008 bid for president, has become a focal point of the select committee’s investigation of Benghazi after her private emails indicated Blumenthal had a direct line to the former secretary of state but Ambassador Chris Stevens, who was killed in the attack, did not.