A veteran GOP lawmaker said Wednesday that if questions over President Trump’s alleged improper influence on an FBI investigation come down to Trump’s word versus that of former FBI director James Comey, that he would be inclined to believe Comey.

Rep. Mike Simpson (R-Idaho), who has spent 18 years in Congress and chairs an appropriations subcommittee, told reporters in the Capitol that he wanted an independent commission to probe the links between Trump and Russia and that Comey ought to testify before Congress in short order.

“I don’t know everything, but everything I know, Comey has the credibility,” he said. “If he’s written this down in memos and so forth, maybe told his chief of staff about it when he wrote it down and stuff, that’s pretty damaging.”

Simpson did not endorse Trump and has criticized him on occasion, but he has also been a reliable supporter of GOP agenda items, including the health-care bill that recently passed the House.

Asked about the implications of reports that Trump may have suggested to Comey that he back off an investigation into former national security adviser Michael Flynn, Simpson said “it depends.”

“I don’t mean to be cute about this, but if the president comes up and says, ‘You know that investigation you’re doing into Flynn? I want it to end,’ that’s one thing,” he continued. “If he comes up and says, ‘You know, I’ve known Flynn for a number of years and he’s a great guy. I hope you can get him past this,’ that’s probably different.”

Asked if the allegations concern potentially impeachable offenses, Simpson said, “I don’t want to go there. I don’t know yet.”

“What I’m worried about is, in the early 1970s, politicians like me were standing around saying, ‘Nixon’s okay, he didn’t do anything,’ and look what it led to,” he said. “And every day there is something that adds on to it.”