Trump contradicted White House statements on Comey's termination but said he wanted the Russia probe to be "so strong and so good."
Sources have named Ayotte as a possible successor to the role, but two high-profile Trump allies are not in contention.
Meanwhile, the FBI raids the offices of a GOP fundraiser with links to Trump.
President says the former FBI director was a 'grandstander' who was going to go no matter what Jeff Sessions and Rod Rosenstein recommended.
Former FBI Director James Comey had been scheduled to speak at the Senate Intelligence Committee hearing before his firing.
Putin addressed Comey's firing in a brief CBS interview.
U.S. president's breaking point was former FBI director's refusal to preview planned Senate testimony for top Trump aides.
The comment came during the White House press briefing held one day after James Comey was fired.
The White House press secretary also asked for the lights to be turned off before he gave a briefing Tuesday night.
The Department of Justice's Office of the Inspector General is looking into why McCabe did not recuse himself from the investigation into Hillary Clinton's use of a private email server.
The fired FBI director leaves as Russia's top diplomat arrives in Washington.
Russian Foreign Minister Sergey Lavrov laughed off a question about the firing of FBI Director James Comey.
So far, even after the controversial firing of FBI Director James Comey, it doesn't look that way.
The pressure may build on Republicans to support an independent investigation into the Trump campaign's alleged Russia ties.
The firing of James Comey could jeopardize the bureau's probe into alleged collusion between the Trump campaign and Moscow, former FBI supervisors say.