Story highlights We might never know what was going through Trump's mind when he fired Comey

But we do know for sure that Comey twice embarrassed the President

Washington (CNN) The White House says President Donald Trump fired FBI Director James Comey because of his treatment of Hillary Clinton. But there's mounting evidence it also had something to do with the continuing investigation by the FBI into the Trump campaign's potential ties to Russia.

CNN's Jake Tapper has reported a source close to Comey says the now-former director never offered his loyalty to President and that the pace of the investigation into alleged Russian connections to the Trump campaign was actually quickening.

We might never know what was going through Trump's mind when he took the unprecedented step.

But we do know for sure that Comey twice embarrassed the President while testifying in front of Congress by directly undercutting something Trump had been pushing.

JUST WATCHED Comey: 'Nauseous' over election thoughts Replay More Videos ... MUST WATCH Comey: 'Nauseous' over election thoughts 01:57

Trump was reportedly furious when Comey said he was "mildly nauseous" at the thought he might have influenced the 2016 election. Comey also said the Russia investigation was continuing, although he wouldn't give specifics.

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