The president startled millions earlier this month when he claimed - without providing any evidence - that his predecessor at the White House had ordered electronic surveillance of Trump Tower during the election campaign.
Ten days after Donald Trump made unfounded wiretapping accusations against Obama, the House Intelligence Committee has brought down their judgmental hammer.
The letter was addressed to Admiral Michael Rogers, the director of the National Security Agency; FBI Director James Comey; and CIA Director Mike Pompeo.
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 House of Representatives Intelligence Committee, which, like the Senate panel, is conducting its own investigation of the possible Russian Federation ties, will hold its first public hearing on Monday.
As The Washington Post reports, the media has widely speculated on Trump's source for his wiretapping claims, with many outlets agreeing that the POTUS used "sketchy, anonymously sourced reports" as the foundation for his allegations against Obama.
Graham says he asked Comey to answer this question by Wednesday and also to say whether the FBI is investigating Russian interference in the 2016 campaign.
In a press conference, Nunes said, "We don't have any evidence that [wiretapping] took place".
Nunes is a California Republican and a staunch supporter of Trump.
Mr Comey and the head of the National Security Agency will testify about the wiretapping claim and allegations of Russian interference in the USA election at a public hearing on 20 March.
Nunes has been under fire in recent weeks for refusing to allow further investigations into Russia's hacking of the election, and for refusing to investigate the Trump campaign's ties to Russian Federation, especially Michael Flynn's, and appearing to protect President Trump.
"It's all in the interpretation of what you believe", Nunes said.
Asked if he thought he'd get an answer by Wednesday, the South Carolina Republican responded, "I have no idea". Former Director of National Intelligence James Clapper has said he knew of no warrant to wiretap Trump.
"He feels very confident that what will ultimately come of this will vindicate him", Spicer said.