Appearing before the House Intelligence Committee alongside National Security Agency Director Mike Rogers, both men confirmed for the first time publicly that the FBI is investigating Russia's involvement with the 2016 presidential election and President TrumPutin's and his associates' connections to Russian Federation.
In January, US intelligence agencies said Kremlin-backed hackers had broken into the email accounts of senior Democrats and released embarrassing ones in order to help Mr Trump defeat Hillary Clinton.
The White House press secretary, Sean Spicer, said earlier this month that Trump was "extremely confident" the Department of Justice would find evidence that the Obama administration wiretapped him before the election.
At last night's public hearing, Mr Comey also said for the first time that the FBI is conducting a broad investigation into Moscow's efforts to "interfere" in the presidential election.
Rep. Chris Stewart pressed the heads of the Federal Bureau of Investigation and National Security Agency about leaks of classified government information during a House committee hearing Monday. "I'll give you a very simple answer", he said when asked about the issue on Fox.
FBI Director James Comey this morning, with the blessing of the Justice Department, took what he said was a step warranted by "unusual circumstances where it is in the public interest" to confirm an open investigation into Russia's campaign op and any ties or collaboration with the Trump team.
Russian Federation denies trying to influence the election, while Mr Trump denounced the investigation as a "total witch hunt".
Mr. Comey has never publicly rejected Mr. Trump's wiretapping claim or publicly acknowledged that it has any kind of investigation under way of contacts between the Kremlin and Mr. Trump's associates.
The Republican chairman of the panel, Mr Devin Nunes, said "the fact that Russian Federation hacked United States election- related databases comes as no shock to this committee".
His tweet came as Federal Bureau of Investigation and National Security Agency chiefs were to speak to Congress on what ties Mr Trump may have with Russian Federation and his as yet unsubstantiated claim that he was wiretapped by his predecessor, Barack Obama.
Comey: "It certainly wasn't our intention to say that today because we don't have any information on that subject, and that's not something that was looked at". The world knows the FBI is investigating, and facts are needed - not tweets, and not speculation.
He added that "will also include an assessment of whether any crimes were committed". Trump campaign officials also met with Russian officials during the Republican National Convention.
Although members of Congress who have been privy to classified briefings have made similar declarations, the director's comment was the first public admission from anyone in a privileged position of knowledge within the USA intelligence community that the President's claim had no basis in fact. "All I can tell you is that we have no information that supports them". Big advantage in Electoral College & lost!