WASHINGTON • President Donald Trump's explosive allegation that his predecessor wiretapped his Manhattan skyscraper wilted further as two high-ranking senators and the top Republican in Congress said they saw no evidence to back the claim.

The Trump administration is facing calls to shore up - or drop - the unsubstantiated claim that former president Barack Obama ordered the phones tapped at Trump Tower during the election campaign.

Yet, White House press secretary Sean Spicer said in a combative exchange with reporters that Mr Trump "stands by" his accusation.

In a statement on Thursday, both Republican Richard Burr, chairman of the Senate Intelligence Committee, and the committee's Democratic vice-chairman Mark Warner said they had seen no information to support Mr Trump's allegation, made in a tweet on March 4. They said: "Based on the information available to us, we see no indications that Trump Tower was the subject of surveillance by any element of the United States government either before or after Election Day 2016."

Their statement came a day after two heads of the House of Representatives Intelligence Committee said they had received no information to back Mr Trump's tweets.

This was echoed by House Speaker Paul Ryan, the top Republican in Congress, who told CNN that "we have not seen any evidence that there was a wiretap" - although he also argued the false claims would not damage Mr Trump's credibility.

"I think the President's going to be marked and judged by his record," Mr Ryan said.

AGENCE FRANCE-PRESSE, WASHINGTON POST