In a blog post Thursday night, Wittes said that at a March 27 lunch meeting Comey expressed concerns about Rosenstein, who served as U.S. attorney for Maryland under both the George W. Bush and Obama administration and was then awaiting confirmation as deputy attorney general.

“His reservations were palpable. ‘Rod is a survivor,’ he said. And you don’t get to survive that long across administrations without making compromises. ‘So I have concerns,'” Wittes wrote, describing his conversation with Comey.

Rosenstein, who was confirmed April 25, has come under fire from Democrats for providing cover for Trump’s firing of Comey. Trump has said he decided to fire Comey before seeking what the president and his aides have called “recommendations” from Rosenstein and Attorney General Jeff Sessions.