James Comey, the FBI director Trump fired last month who was overseeing a federal investigation into connections between Russia and the Trump campaign, will testify June 8 at a congressional hearing, it was revealed on Thursday.
The FBI's investigation is one of several probes into Russia's alleged involvement in the 2016 election. The House intelligence committee and the U.S. Department of Justice, via recently appointed special counsel Robert Mueller, are also investigating.
The Senate intelligence committee announced Comey's appearance, and a Comey associate said he had been cleared to testify by Mueller.
Comey's testimony could shed light on his private conversations with the president in the weeks before the dismissal.
Comey's associates have said Comey told them that Trump asked him at a January dinner to pledge his loyalty to the president and, at an Oval Office meeting weeks later, asked Comey to consider ending an FBI investigation into Trump's first national security adviser, Michael Flynn.
The White House has denied those characterizations.
- Request for Russia back channel troubles experts
- Comey's revenge: Why 'Trump has bigger problems now'
Mueller's investigation could include a look at the circumstances of Comey's firing, especially since Trump has said publicly that he was thinking of "this Russia thing" when he made the move.
Trump's Attorney General Jeff Sessions is also under scrutiny for not being forthright. Sessions has acknowledged two meetings with Sergey Kislyak, the Russian ambassador to the United States, but some Democratic senators have pointed to the possibility of a separate encounter at an April 2016 Trump campaign event that Sessions and Kislyak attended.
The Justice Department has acknowledged that Sessions was at the Mayflower Hotel event in Washington, but said there were no private or side conversations that day.
Meanwhile, Britain's Nigel Farage, a leading Brexit campaigner, is a "person of interest" in the U.S. investigation into possible collusion between Russia and Trump's campaign, the Guardian reported on Thursday, citing unidentified sources.
Linked to Assange
The Guardian said Thursday that Farage had not been accused of wrongdoing and was not a suspect or target of the U.S. investigation.
But it said the former leader of the United Kingdom Independence Party (UKIP) had "raised the interest" of FBI investigators because of his relationships with individuals connected to both the Trump campaign and WikiLeaks founder Julian Assange.
Farage told the Guardian: "I consider it extremely doubtful that I could be a person of interest to the FBI as I have no connections to Russia."
When asked about the Guardian report, a UKIP spokesman said it was absurd.
"To my knowledge, the only serious Russian politician that Nigel has spent time with is Garry Kasparov," the spokesman said.
CIA Director Mike Pompeo has accused Assange's WikiLeaks of seeking to interfere in the U.S. election when it distributed material hacked from Democratic National Committee computers during the 2016 campaign.
Pompeo said Russia's GRU military intelligence service used WikiLeaks to distribute the material and concluded that Russia stole the emails and took other actions to tilt the election in favour of Trump, a Republican, over Democratic candidate Hillary Clinton.
Farage, who has campaigned for decades for Britain to leave the European Union, was a vocal backer of Trump. He met Trump in New York just days after the election and attended the inauguration in Washington.
Putin denies hacking on 'state level'
Farage met Assange in March this year at the Ecuadorean Embassy in London where he has been holed up for five years.
Russian President Vladimir Putin has denied leading efforts to interfere in last year's U.S. election., but reworded his denial on Thursday when he remarked that "patriotic" Russian hackers could have been involved, without the Kremlin's knowledge.
"We don't engage in that at the state level," Putin said during a meeting with senior editors of several international news agencies.
Trump, a Republican, has denied any collusion between Russia and his campaign and has repeatedly questioned the U.S. intelligence finding that Putin led an operation that included computer hacking, fake news and propaganda intended to swing the election in Trump's favour.
The chairman of the House committee raised eyebrows on Wednesday when he issued subpoenas to the FBI, the CIA and the National Security Agency. Representative David Nunes, a California Republican, asked for details about any requests by three top officials under the Obama administration to "unmask" Trump campaign advisers who were inadvertently picked up in top-secret foreign communications intercepts.
Nunes, in April, recused himself from leading the panel's investigation following a secret visit he paid to White House officials, but he retains subpoena power.
Democrats on the committee complained they were not informed about the subpoenas. A congressional source, who requested anonymity, said they were "informed and consulted" ahead of time.
Trump on Thursday sounded his support for the subpoenas, tweeting that "unmasking and surveillance" under Obama is the "big story."