White House is 'almost 100% certain' Trump has not spoken to FBI's Comey since wiretapping claim

President Donald Trump has likely not talked to FBI Director James Comey since making the explosive and unsubstantiated Saturday claim that predecessor Barack Obama had Trump Tower's "wires tapped" before the 2016 presidential election, the White House said Monday.

Comey asked the Justice Department to publicly reject Trump's accusations, a senior U.S. official confirmed to NBC News.

"I'm almost 100 percent certain" that Trump and Comey have not spoken since Saturday, White House press secretary Sean Spicer told reporters Monday in an off-camera briefing. He also cast doubt on whether Comey really approached the Justice Department about the accusations, saying "I don't know" if that occurred.

Spicer added that Trump has told him "nothing" to suggest that he has lost confidence in the FBI director.

Trump has not given any evidence to back up the claim, while a spokesman for Obama has denied that he ordered wiretapping of Trump. Spicer did not give any more specific evidence and said he wanted to see how a congressional investigation into the matter, which the White House urged, will play out.

Politicians on both sides of the aisle have sought more information on Trump's claim.

Watch: Trump's claim destructive, says pro