The White House press secretary, Sean Spicer, sparred with reporters in a contentious Thursday press briefing over President Donald Trump's explosive wiretapping claims, on which Senate leaders from both parties cast doubt earlier in the day.

Spicer had confrontational back-and-forth exchanges with several reporters, including ABC's Jonathan Karl and CNN's Jim Acosta, the latter of whom Trump has previously referred to as "fake news."

Karl began by asking Spicer about the Senate Intelligence Committee leaders' Thursday statement saying there were "no indications" Trump was wiretapped, which the president accused President Barack Obama of illegally doing before the election.

Earlier in the week, Spicer said he was "extremely confident" the Department of Justice would find evidence to back up Trump's claim.

Spicer launched into a minutes-long rant after Karl presented him with this information; Spicer said the media did not cover similar statements from the agencies when they were in favor of Trump's position on an issue, such as possible ties to Russia. When something has the opposite slant, Spicer said, it is covered "ad nauseam."

He also insisted the president, who said as much in a Wednesday interview with Fox News host Tucker Carlson, meant surveillance generally when he tweeted about wiretapping. At one point, Spicer engaged in a shouting match with Karl and asked the ABC White House correspondent to "calm down."

Spicer then cited numerous sources he believed backed up the White House's side of the argument. He listed reports from The New York Times, Heat Street, and Circa News, as well as a diatribe from unabashed pro-Trump Fox News host Sean Hannity.

Karl followed up after the lengthy rehashing of news reports, asking whether the president still stood by his allegation even after both the House and Senate intelligence committees suggested it was untrue. Spicer said the "House and the Senate has not been provided all the information," prompting a rebuke from a representative of the Senate Intelligence Committee vice chair, Democratic Sen. Mark Warner of Virginia.

"The bipartisan leaders of the Intelligence Committee would not have made the statement they made without having been fully briefed by the appropriate authorities," the representative said.

Spicer said Trump still stood by his assertion, circling back to asking Karl why he wasn't "coming to the defense" of the intelligence committees when they were disputing connections to Russia.

That's when Acosta followed up.

"You were just quoting Sean Hannity there," he said, later adding Spicer was also citing Fox News contributor Andrew Napolitano.

Spicer said Acosta was "cherry-picking" the sources he was citing, reiterating that he listed The New York Times.

But Acosta went back to mentioning what was stated by the intelligence committees, refuting Trump's assertion.

Spicer continued doubling down on his previous points.

"That sounds like, Sean, what you and the president are saying is, 'Well, we don't mean wiretapping anymore because that's not true anymore,'" Acosta said.

"No, no, that's not true!" Spicer exclaimed.

"What's it going to be next?" Acosta asked.

Spicer called that question "cute" but said the point about what Trump meant by his tweets had been discussed in the briefing room for days.

The press secretary later added that Acosta was coming to "serious conclusions" about Trump's assertions "for a guy that has zero intelligence."

Some in the room broke out in laughter.

"Give me some credit, Sean, a little intelligence maybe," Acosta said.

Spicer added with a smile that he meant to include "clearance" in his statement.

"You seem to know all the answers," Spicer said.

Watch part of Spicer's briefing below: