The first Republican lawmaker has called for an independent investigation into possible contacts between Donald Trump’s associates and the Russians during last year’s election, while the White House says there’s nothing to the various claims.

Rep. Darrell Issa, R-Calif., speaking this weekend on HBO’s Real Time With Bill Maher, praised new Attorney General Jeff Sessions, but noted that he worked on Trump’s campaign and may have an inherent conflict of interest.

“You’re going to need to use the special prosecutor’s statute and office,” Issa said, adding that “you can’t just give it to your deputy. That’s another political appointee.”

Trump and aides have rejected the idea of an outside investigation, and said that there were no contacts between campaign aides and Russian operatives involved in efforts to interfere with the 2016 election.

Trump himself disputed news reports in a tweet Sunday: “Russia talk is FAKE NEWS put out by the Dems, and played up by the media, in order to mask the big election defeat and the illegal leaks! “

The FBI is already conducting an investigation of Russian election activity, as are Senate committees.

Issa, who struggled last year to win re-election in a district carried by Democratic presidential candidate Hillary Clinton, spoke about the Russia investigation after news reports of a discussion of the case between the FBI and White House Chief of Staff Reince Priebus.

The White House said an FBI official approached Priebus to deny news reports about contacts between Trump associates and the Russians; Priebus asked the FBI to make that statement publicly; the FBI said it didn’t want to get into the habit of commenting on ongoing investigations.

“They came to us, they approached us for putting that story out there,” said White House spokeswoman Sarah Sanders, speaking on ABC’s This Week. “I think the American people deserve to know the truth.  And that’s exactly what it is, that there’s nothing here. Just because reporters say something over and over and over again doesn’t start to make it true.”

Congressional Democrats have long called for an outside investigation.

House Democratic leader Nancy Pelosi, D-Calif., speaking on ABC’s This Week, said there should be at least an “independent commission” designed “to study the personal, political, and financial relationship between President Trump and the Russians.”

New Jersey Gov. Chris Christie, R-N.J., an ally of Trump, told CNN’s State of the Union that the Justice Department has plenty of career, non-partisan professionals to conduct this type of investigation. He also said that past independent counsel investigations have generated problems of their own.

“When a special prosecutor gets involved,” Christie said, things could get “completely out of control.”