Senior US Democrats and Republicans have said they had seen no evidence to support President Donald Trump's claim that the Obama administration wiretapped his New York home and office building.
"We don't have any evidence that that took place," said Devin Nunes, Republican chairman of the congressional committee conducting an inquiry into the allegation.
At a press conference he said: "I don't think there was an actual tap of Trump Tower."
Mr Nunes' conclusion was echoed by the panel's top Democrat, Adam Schiff.
"To date I've seen no evidence that supports the claim that President Trump made that his predecessor had wiretapped he and his associates at Trump Tower," Mr Schiff said.
"Thus far, we have seen no basis for that whatsoever."
The House Intelligence Committee, which Mr Nunes heads, is also conducting an investigation into suspected Russian interference in last year's US election.
On 4 March, Mr Trump sparked a furore when wrote on his @realDonaldTrump Twitter account that Mr Obama had tapped into communications at Trump Tower, New York home to the president and first family, before the 8 November election.
The tweets sparked enormous controversy, in part because it is unprecedented for any US president to accuse a predecessor of a felony crime.
Terrible! Just found out that Obama had my "wires tapped" in Trump Tower just before the victory. Nothing found. This is McCarthyism!
— Donald J. Trump (@realDonaldTrump) March 4, 2017
Is it legal for a sitting President to be "wire tapping" a race for president prior to an election? Turned down by court earlier. A NEW LOW!
— Donald J. Trump (@realDonaldTrump) March 4, 2017
How low has President Obama gone to tapp my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!
— Donald J. Trump (@realDonaldTrump) March 4, 2017
The allegation was also remarkable since Mr Trump - although known for making bombastic, unsubstantiated claims via the social messaging platform - would, as president, have access to secret law enforcement and intelligence probes containing such information.
The US President made his allegations just after reports in conservative media made the same claim, leading to suspicions they were his source - which the White House has not denied.
"It deeply concerns me that the president would make such an accusation without basis," said Mr Schiff.
Mr Nunes and Mr Schiff said they do not expect to hear evidence backing up the claim when Federal Bureau of Investigation Director James Comey testifies to the House Intelligence Committee on Monday.
But the two said they are hoping to make progress on the issues of Russia's interference in last year's election, including how many people linked to the Trump campaign may have been wiretapped in the course of that or other probes.
Also testifying Monday will be Michael Rogers, director of the National Security Agency, the government's electronic spying body.
Another intelligence hearing, with testimony from other witnesses, is scheduled for 28 March.
Mr Trump seemed to back away from his accusation of wire tapping in a Fox News interview, saying "wiretap covers a lot of different things."
Without providing details, the President added, "I think you're going to find some very interesting items coming to the forefront over the next two weeks," according to excerpts of the interview.
