"I am even more convinced that the FBI did exactly what my fellow citizens would want them to do when they got the information they got," said Gowdy, one of just five Republicans in a classified DOJ briefing last week for congressional leaders about the issue.

Wednesday morning, Gowdy doubled down on CBS.

"When the FBI comes into contact with information about what a foreign government may be doing in our election cycle, I think they have an obligation to run it out," he said.

The lawmaker's comments were echoed by Napolitano, who said Trump's "spy" claim seemed to be "baseless" and that the use of an informant on the periphery of the campaign is "standard operating procedure" in the FBI's counterintelligence operations.

"If they were there for some nefarious reason ... to gather data from the campaign and pass it to the West Wing and pass it to Mrs. Clinton, I'd want to see evidence of that before I made an allegation that outrageous," Napolitano said.

Dershowitz joined in Wednesday morning by conceding that he was "on the way to being persuaded" that the FBI's use of an informant was proper.

The confluence of conservative defenses of the FBI undercuts Trump's aggressive PR strategy to undercut special counsel Robert Mueller's ongoing probe into Russian election meddling and whether there was any coordination with the Trump campaign. That investigation has edged deeper inside Trump's inner circle and spurred Trump to lash out against the "witch hunt" against him.