President Donald Trump's explosive allegation that Barack Obama wiretapped his New York skyscraper during the presidential campaign has left him increasingly isolated, with allies on Capitol Hill and within his own administration offering no evidence to back him up.
On Wednesday, Attorney General Jeff Sessions said he had not given Trump any reason to believe he was wiretapped by President Obama. Republican Devin Nunes, chairman of the House intelligence committee, said he had seen no information to support the claim and suggested the US president's assertion, made in a series of March 4 tweets, should not be taken at face value.
"Are you going to take the tweets literally?" Nunes said. "If so, clearly the president was wrong."
But Trump seemed to stand by his claims, saying in an interview with Fox News there would be "some very interesting items coming to the forefront over the next two weeks."
Trump's allegations have put him in a potentially perilous position as congressional investigations into Russia's involvement in the 2016 election - and possible Russian contacts with Trump associates - ramp up. The FBI is also investigating.
If no evidence of wiretapping at Trump Tower emerges, his credibility would be newly damaged.
If there is proof that the Obama administration approved monitoring of Trump or his associates, that would suggest the government had reason to be suspicious of their contacts with Russia and a judge had approved the surveillance.
The president, who appears to have made his allegation in a burst of anger, has asked lawmakers to investigate the claim. Lawmakers have since turned the question back toward the administration, asking the Justice Department to provide evidence of wiretapping activity.
The Justice Department missed a Monday deadline for providing the information to the House and was given a one-week extension.
