It will further fuel investigations into possible Trump campaign ties with Russian Federation - because his credibility will be so far underwater that it touches seaweed on the ocean floor.
Pressed at the White House briefing on whether Mr Trump would back down from his wiretap accusations, Mr Spicer said: "He stands by it".
GOP Rep. Devin Nunes and Democratic Rep. Adam Schiff say they're still waiting for evidence from the Justice Department backing up that claim.
A spokesman for Britain's prime minister says the White House has promised that it won't repeat a claim that United Kingdom spies snooped on U.S. President Donald Trump.
Graham, of SC, is leading one of three congressional investigations into Russia's interference in the 2016 election.
Instead, Trump, standing alongside German Chancellor Angela Merkel, whose cellphone had been tapped by the Obama administration, said at a news conference: "As far as wiretapping, I guess, by this past administration, at least we have something in common, perhaps".
Spicer read aloud to reporters news reports from recent months that suggested there could have been spying on Trump Tower or the Trump campaign, and said people should wait for the formal conclusion of any investigations.
Spicer and Trump's national security adviser, Army Lt. Gen. H.R. McMaster, told British officials that Spicer was "simply pointing to public reports, not endorsing any specific story".
Burr is the committee's Republican chairman; Warner is its ranking Democrat. "That really covers, because wiretapping is pretty old-fashioned stuff, but that really covers surveillance and many other things", he said.
Week of hearings, testimonies and votes on agenda for Trump administration
Adam Schiff, the ranking member on the House intelligence committee, also agreed there was no evidence to back up the accusation. The Senate intelligence committee and the Federal Bureau of Investigation also are probing Russian involvement in the election.
"As I told you last week about the issue with the president talking about tapping Trump Tower, that evidence still remains the same, that we don't have any evidence that that took place", Nunes told reporters.
"They are not findings", he said.
Asked whether Trump's communications may have been swept up in surveillance, Nunes said it was "very possible".
"The Department of Justice has complied with the request from leaders of the House and Senate Intelligence Committees and Judiciary Committees seeking information related to surveillance during the 2016 election", Justice Department spokeswoman Sarah Isgur Flores said Friday, CNN reported.
Obama's spokesman has denied wiretapping, noting that presidents are prohibited by law from wiretapping and that such surveillance would have to be approved by a special court.
"There was no such wiretap activity mounted against the president-elect at the time as a candidate or against his campaign", Mr. Clapper said last week on NBC's "Meet The Press".
"Well, because the New York Times wrote about it", Trump replied.
On Wednesday, Trump said "some very interesting items" were coming in the coming weeks that would prove his claim, which has been widely decried by his critics as baseless. It does not say Obama ordered this surveillance, nor does it say Trump's own phones were tapped or that he was under surveillance in any way.