Trump has ridiculed the probe, as well as concurrent congressional investigations, as a "hoax" and has denied that his campaign was involved in Russia's election meddling. It did not state exactly why he was being fired, merely saying he was "not able to effectively lead the Bureau".
The White House released a memo by Deputy Attorney General Rod Rosenstein that provided the administration's justification for firing Comey.
Initial reactions to Comey's firing tended to fall along party lines.
Democrats compared the ouster to Nixon's decision to fire the independent special prosecutor overseeing the Watergate investigation in 1973, which prompted the resignations of the Justice Department's top two officials. Yet, some bipartisian criticism did emerge.
The White House and the Justice Department cited Comey's ineffective leadership, but the general gist of Democratic reaction: Trump's decision should be viewed not in light of Comey's past missteps but instead in the context of the FBI's ongoing investigation into Russian meddling in the USA election and the Trump transition team's possible ties to Russia.
One week ago, Clinton said during a forum that she was "on the way to winning until a combination of Jim Comey's letter on October 28 and Russian WikiLeaks raised doubts in the minds of people who were inclined to vote for me but got scared off". Several Republicans joined them in raising alarms of how it could affect probes into possible coordination between Trump associates and Russian Federation to influence the 2016 presidential election. Comey, serving as acting attorney general while Ashcroft was hospitalized, went there to block senior Bush administration officials who had hoped to make an end run around him by getting Ashcroft's permission to reauthorize a secret no-warrant wiretapping program. "Now more than ever, it is vital that our ongoing investigation is completed in a credible and bipartisan way". For Mr. Trump, firing Mr. Comey is fraught with risks.
He called for an immediate open hearing in which Comey would testify about the status of the Russian Federation investigation at the time of his firing.
The fact that the White House is claiming this is what happened is ludicrous - and, as my colleague Matt Yglesias observes, ludicrous in a particularly telling way. The move could intensify public worry about the course of the Russian Federation investigation, while igniting concerns that Mr. Trump is seeking to use his power to sideline a potential threat.
"Deputy Attorney General Rosenstein now has no choice but to appoint a Special Counsel". Susan Collins said in a statement. "This investigation must be independent and thorough in order to uphold our nation's system of justice".
The Justice Department inspector general has been investigating Comey's handling of the Clinton email investigation and other campaign controversies since last fall, but the rapid-fire events on Tuesday added a historic level of drama to a story that has gripped Washington for months.
It was an unexpected predicament for the man who had painted ethical decision-making as an easy call.
The White House said that the search for a new Federal Bureau of Investigation director would begin immediately. He could partner with Trump and Sessions on anti-terrorism efforts. "Unfortunately, this has clearly been lost". "We have had a great relationship with him over the last several weeks".
Some lawmakers did welcome news of the dismissal. "He's wrong", she told CNN. He called the former director "Gutsy", for pursuing the case.
In near-unanimity, Democrats are calling for a special prosecutor to take charge of the FBI's investigation, which Comey made public earlier this year when testifying in front of the House Intelligence Committee.
With public opinion turning on him over the Clinton email investigation, however, Comey appeared to realize that he was becoming increasingly isolated after years of stardom.
The new director must be appointed by Trump and confirmed by the U.S. Senate.
California Sen. Dianne Feinstein, who blasted Comey during that hearing, was notably much more muted than her fellow Democrats Tuesday night.
"I was nonjudgmental until the last 15 minutes", Rep. Tim Walz (D-MN.), ranking member of the Veterans Affairs Committee, said.