(UPDATED) Former FBI director James Comey on Thursday accused President Donald Trump of firing him to try to undermine the bureau's investigation into possible collusion between his 2016 presidential campaign team and Russia.
Comey also told senators in the most eagerly anticipated U.S. congressional hearing in years that the Trump administration had told lies and defamed him and the FBI after the president dismissed him on May 9.
The administration gave differing reasons for Comey's firing. Trump later contradicted his own staff and acknowledged on May 11 that he fired Comey because of the Russia probe.
Asked at a U.S. congressional hearing why he was fired, Comey said he did not know for sure. But he added: "Again, I take the president's words. I know I was fired because of something about the way I was conducting the Russia investigation was in some way putting pressure on him, in some way irritating him, and he decided to fire me because of that."
Comey earlier told the Senate Intelligence Committee that he believed Trump had directed him to drop an FBI probe into the Republican president's former national security adviser Michael Flynn as part of the Russia investigation.
But Comey would not say whether he thought the president sought to obstruct justice.
"I don't think it's for me to say whether the conversation I had with the president was an effort to obstruct. I took it as a very disturbing thing, very concerning," Comey told the committee.
Trump critics say that any efforts by the president to hinder an FBI probe could amount to obstruction of justice. Such an offense potentially could lead to Trump being impeached by Congress, although the Republicans who control the Senate and House of Representatives have shown little appetite to make such a move against him.
Dressed in a dark suit and giving short, deliberative answers, Comey painted a picture of an overbearing president who pressured him to stop the FBI looking into Flynn.
In more than two hours of testimony, Comey did not make any major new revelations about alleged links between Trump or his associates and Russia, an issue that has dogged the president's first months in office and distracted from his policy goals such as overhauling the U.S. healthcare system and making tax cuts.
Trump, in a speech across town, told supporters their movement was "under siege" and vowed to fight on.
"We're under siege ... but we will come out bigger and better and stronger than ever," he said. "We will not back down from doing what is right."
"We know how to fight and we will never give up," the president added.
U.S. stocks were higher in early afternoon trading on Thursday after investors concluded Comey's testimony would not by itself bring down Trump's presidency.
Comey's accusations could further mire Trump's administration in legal difficulties, as special counsel Robert Mueller and several congressional committees investigate alleged Russian efforts to influence the 2016 presidential election and whether Trump's campaign colluded with Moscow.
Russia has denied such interference and the White House as denied any collusion.
The former FBI head said Trump's administration had defamed him in comments made after his firing by saying that the bureau was in disarray and that the workforce had lost confidence in its leader. "Those were lies, plain and simple," Comey said.
Comey said Trump did not attempt to get him to drop the overall Russia investigation, just the part of if that related to Flynn, who the president fired in February for misleading Vice President Mike Pence about the extent of his conversations last year with Russia's ambassador to the United States.
Republican Senator Marco Rubio asked Comey whether he perceived the president's request to let the Flynn matter go as an order given Trump's position as president, the setting and the circumstances surrounding the conversation.
"Yes," Comey replied.
As Comey was testifying, a White House source said Trump disputes two key points in Comey's testimony: that he asked the FBI director to let go of the Flynn probe, and that he asked for Comey's loyalty.
Trump’s son Donald Trump Jr. fired off a series of tweets attacking Comey but the president himself stayed off social media while the drama played out in Congress.
Comey said he felt he needed to get his account of his conversations with Trump in the public sphere in the hope that it might prompt the appointment of a special counsel, which later occurred. Comey said he showed copies of his memo memorializing his talks with Trump to people outside the Justice Department and "asked a friend of mine to share the content of the memo with a reporter."
Comey said he shared the memo with "a professor at Columbia Law School, a reference to Daniel Richman, who confirmed to Reuters he was the person Comey referred to in his testimony.
Comey said he did not know if there are tapes of his conversations with Trump but said he hoped there were and that they should be made public.
"Lordy, I hope there are tapes," Comey said.