Trump admitted that he fired Comey out of frustration with the Russia investigation.

“President Donald Trump has said he was thinking of ‘this Russia thing’ when he decided to fire FBI Director James Comey, who had been leading the bureau’s investigation into alleged Russian meddling in the 2016 election.  Trump told NBC News that he was frustrated by the ongoing investigation and believed it was motivated by Democrats’ fury at losing the election. Trump told NBC’s Lester Holt: ‘And in fact when I decided to just do it, I said to myself, I said ‘you know, this Russia thing with Trump and Russia is a made-up story, it’s an excuse by the Democrats for having lost an election that they should have won.’”

Trump told the Russian foreign minister and ambassador that firing Comey eased the pressure of the Russia investigation.

“President Trump told Russian officials last week that he had fired the ‘nut job’ FBI Director James Comey to ease the pressure of the mounting investigation into his campaign’s ties to Russia, according to a report from The New York Times.  ‘I just fired the head of the F.B.I. He was crazy, a real nut job,’ Trump told the Russian foreign minister and U.S. ambassador on May 10 during an Oval Office meeting, according to a transcript of the meeting read to The Times by a U.S. official. ‘I faced great pressure because of Russia. That’s taken off.’”

Trump was openly fuming about the Russia investigation just days before he met with Sessions and Rosenstein to discuss Comey’s firing

“[Trump] had grown enraged by the Russia investigation, two advisers said, frustrated by his inability to control the mushrooming narrative around Russia. He repeatedly asked aides why the Russia investigation wouldn’t disappear and demanded they speak out for him. He would sometimes scream at television clips about the probe, one adviser said.   Trump’s firing of the high-profile FBI director on the 110th day after the president took office marked another sudden turn for an administration that has fired its acting attorney general, national security adviser and now its FBI director, whom Trump had praised until recent weeks and even blew a kiss to during a January appearance.”

Deputy Attorney General Rod Rosenstein knew Trump would fire Comey before he manufactured the Clinton email excuse.

“Deputy Attorney General Rod Rosenstein said Thursday that he knew President Trump would fire former FBI Director James Comey before he issued a memo recommending his removal, according to several senators briefed by Rosenstein.  ‘He did acknowledge that he knew Comey would be removed prior to him writing his memo,’ Sen. Claire McCaskill, D-Missouri, said, after leaving a closed-door briefing with Rosenstein for the full Senate on Capitol Hill.  She added that Rosenstein declined to provide details about Comey’s dismissal because she said Rosenstein is anxious to give wide latitude to former FBI Director Robert Mueller, who Rosenstein appointed as special counsel Wednesday to investigate Russian interference in the 2016 U.S. election”