But Nunes is so deep in the tank for Trump that he needs scuba gear. With his words and deeds, he has labored mightily to redirect attention from Trump’s alleged wrongdoing to his claims of persecution, recasting villain as victim. It’s Trump’s gratitude that he’s after, not the truth.

When politicians on both sides of the aisle upbraided Trump for his baseless accusations about the wiretapping of Trump Tower, Nunes swooped in to say, “I don’t think we should attack the president for tweeting.” But Twitter was hardly the issue. The president’s paranoid hallucinations were.

When James Comey, the F.B.I. director, appeared before Nunes’s committee to confirm his own agency’s investigation into Trump-Russia ties, Nunes changed the subject to the media’s acquisition of classified information, going on about leaks, leaks, leaks. He sounded more like a plumber than a politician.

And when Nunes gathered reporters around him two days later, it was to say that he’d seen secret documents suggesting that people around Trump may indeed have been subject to surveillance by our government.

This was Nunes at his most irresponsible. To the casual listener, he was insinuating that Trump’s wiretapping charges weren’t so very far from the mark. But they were, and Nunes had to acknowledge that as he clarified his remarks. He was talking about the surveillance of Americans who happened to be in contact with foreign players whose communications were the real subjects of concern. He had no evidence — zilch — of any eavesdropping that targeted Trump.

This week we learned that Nunes got that information during that rendezvous, details of which he has not provided to his fellow committee members, just as he failed to share the information itself with Democrats on the committee before he went public with it.

All of this is irregular enough to peg him as a puppet of the Trump administration or a complete boob. Either way, he has surrendered his investigation’s integrity — and his own.