In his recommendation to Mr Trump, Deputy Attorney General Rod J Rosenstein said that over the past year, the FBI's reputation and credibility suffered substantial damage, and it has affected the entire department of justice.
"That is deeply troubling to many department employees and veterans, legislators and citizens," he said.
Soon after receiving the letter, Mr Trump dismissed Mr Comey.
"The president had lost confidence in Director Comey.
Frankly, he'd been considering letting Director Comey go since the day he was elected," White House Principal Deputy Press Secretary Sarah Sanders told reporters at a news conference yesterday.
However, she acknowledged that Mr Trump did have a conversation with the deputy attorney general.
"The president asked that they put those concerns and their recommendation in writing," she said, referring to the letter which became the basis for firing Mr Comey.
Mr Trump told reporters that Mr Comey was not doing a good job.
Ms Sanders told reporters that most of America had decided on their own that Mr Comey was not the person that should be leading the FBI, as evidenced by the numerous comments that they have seen from Democratic party members in the House and Senate, Republican members, members of the FBI, and people across the board.
"I think one of the big catalysts that we saw was last week, on Wednesday, director Comey made a pretty startling revelation that he had essentially taken a stick of dynamite and thrown it into the department of justice, by going around the chain of command when he decided to take steps without talking to the attorney general or the deputy attorney general, when holding a press conference and telling them that he would not let them know what he was going to say.
"That is simply not allowed," Ms Sanders said.
Meanwhile, Mr Comey has been invited by a powerful Congressional committee to testify before lawmakers at a closed session on Tuesday.
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