The existence of an investigation isn't a surprise, but Comey's announcement Monday is the first time the FBI has acknowledged an active case. "I have seen nothing on the NSA side that we engaged in any such activity nor that anyone ever asked us to engage in such activity", Rogers told the committee.
The president created a controversy in early March when he tweeted without giving evidence that Obama had wiretapped the campaign as the Republican businessman took on Democrat Hillary Clinton in the presidential race.
Mr Nunes told Fox News on Sunday that a review of justice department documents provided on Friday indicated there was no such wiretap.
FBI Director James Comey and National Security Agency Director Mike Rogers will testify on-the-record under oath starting at 9 a.m.
Russian Federation denies trying to influence the election, while Mr Trump denounced the investigation as a "total witch hunt".
Trump said Congress instead should be investigating leaks that have harmed his young administration. He also went on reject the president's claims that the Obama administration "wiretapped" Trump Tower past year, saying, "Let me be clear: we know there was not a wiretap on Trump Tower". "Must find (the) leaker now!" he said. Trump tweeted early Monday as news coverage on the Russian Federation allegations dominated the morning's cable news.
FBI Director James Comey waits to speak during the House Permanent Select Committee on Intelligence hearing on Russian actions during the 2016 election campaign. US intelligence officials have not publicly raised the possibility of contacts between the Clintons and Moscow.More news: US To Ban Electronics On Certain Flights
USA intelligence agencies are confident that Russian Federation directed hacks into the Democratic National Committee and campaign officials for Democratic presidential candidate Hillary Clinton.
Donald Trump had made several explosive claims on Twitter earlier this month in which he accused then president Barack Obama of wiretapping his phones last October likening it to the Watergate scandal.
"The Department of Justice and Trump administration must allow Director Comey's investigation to move forward without any interference, meddling, or political pressure of any kind whatsoever", Senate Minority Leader Chuck Schumer said. "There is direct evidence, I think, of deception and that's where we begin the investigation".
Mr Nunes said: "For the first time, the American people, and all the political parties now, are paying attention to the threat that Russian Federation poses". "The one crime we know that's been committed is that one, the leaking of someone's name", Nunes said. "They're also trying to get involved in campaigns around the globe and over in Europe", he said on "Fox News Sunday".
Committee Chairman Devin Nunes (R-Calif.) kicked off the hearing saying that Russian interference in the election "comes as no shock to this committee" but remains "deeply troubling".
Although the FBI does not typically comment publicly on the status of its investigations, Comey stated that the bureau's inquiry into the Trump administration's possible collusion with another foreign power is a matter of public interest.