The House Intelligence Committee says it has seen no evidence to support Donald Trump's claim that his phones were wiretapped.
Republican Congressman Devin Nunes and Democratic Congressman Adam Schiff, who lead the committee, have said they are still waiting for evidence from the US Justice Department.
The department has until 20 March to comply with a request for evidence, but could be compelled to do so by the committee if it misses the deadline.
Mr Nunes said he did not believe there was "an actual tap of Trump Tower" in New York, which President Trump claimed on his Twitter account on 4 March.
At the time, Mr Trump wrote: "How low has President Obama gone to tapp my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!
"I'd bet a good lawyer could make a great case out of the fact that President Obama was tapping my phones in October, just prior to election!
"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!"
Mr Nunes said the committee was battling with the Office of the Director of National Intelligence to get access to computer technology so they can go through CIA evidence on alleged Russian interference in the election.
Last Monday, FBI director James Comey apparently asked the US Justice Department to publicly refute Mr Trump's accusations - a move which called into question the US President's truthfulness.
That followed comments from James Clapper, the director of national intelligence in the Obama administration, who denied there had been an order for surveillance at Trump Tower.
Mr Comey and the head of the National Security Agency will testify about the wiretapping claim and allegations of Russian interference in the US election at a public hearing on 20 March.