Sanders, speaking Thursday on "CBS This Morning," said Trump decided to dismiss Comey this week after a "consistent erosion of confidence in his ability to do his job," and that similar sentiment was evident in the bureau's rank-and-file.
"Let's not forget there was a near uprising after Comey from members of the FBI," the deputy press secretary said. "This isn't just about the president losing confidence. The rank-and-file members within the FBI had lost confidence in the director."
While Sanders reiterated her insistence that Comey's termination had nothing to do with the investigation into possible collusion between Russia and Trump's presidential campaign, she said Comey had become a "much bigger distraction" than the investigation itself was, and noted his appearance before a Senate panel last week required formal correction.
RELATED: Reaction to Trump's firing of James Comey
Reaction to Trump's firing of James Comey
Reaction to Trump's firing of James Comey
But does anyone seriously believe @realDonaldTrump fired the top person investigating his ties to Russia because he was unfair to Hillary?
Trump firing Comey shows how frightened the Admin is over Russia investigation
Gov. John Kasich statement on James Comey https://t.co/Wrwj6sGqnz
Removal of Director Comey only confirms need for select cmte to investigate #Russia's interference in 2016 election https://t.co/LfKlwSw6iQ
EVERYONE who cares about independence & rule of law in America should be "troubled by the timing and reasoning" of… https://t.co/NZY4qh3uiz
This is Nixonian. Deputy AG Rod Rosenstein must immediately appoint a special prosecutor to continue the Trump/Russia investigation.
Firing of Comey tainted by extraordinary conflict of interest. Independent prosecutor must be appointed to restore… https://t.co/lXBIJtTf18
First Pres Trump fired Sally Yates, then Preet Bharara. Now #Comey. Doesn't seem like an accident. We must have a special prosecutor.
If we don't get a special prosecutor, every American will rightfully suspect that the decision to fire #Comey was part of a cover-up.
We are in a full-fledged constitutional crisis.
Comey's fired, which means Trump must be one of the few people in DC that the FBI doesn't have something on.
My statement on James Comey https://t.co/NWBR8FGTCf
Elijah Cummings is calling for "immediate emergency hearings". https://t.co/iMsNmdPmHi
LEAHY: "This is nothing less than Nixonian." https://t.co/n4R4fWSgib
Sen. John McCain on Comey firing: "I regret that that took place. The president does have that authority, so I resp… https://t.co/pSEu3XXsj5
Statement on FBI Director Comey ➡ https://t.co/vB822Nw5OR
This should not be sugar coated. Firing Comey is up there in terms of the scariest things Trump has done.
I am troubled by the timing and reasoning of Director Comey’s termination.
My staff and I are reviewing legislation to establish an independent commission on Russia. The second paragraph of… https://t.co/qcm1PiFkNG
Ds were against Comey before they were for him.
U.S. Senator Susan Collins’ Statement on Director Comey
Firing Comey has the foul stench of an attempt to stop an ongoing investigation into collusion between the Trump campaign and the Russians.
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"This is something, frankly, after Wednesday's testimony, [Trump] was very engaged on and certainly he had been pushed to the point where he was ready to make that decision," she said. "He had a conversation on Monday with the attorney general [Jeff Sessions] and deputy attorney general [Rod Rosenstein] and asked them for their thoughts, their feedback."
Sanders also said Comey's dismissal would not interrupt the Russia investigation.
"Any investigation taking place on Monday is still taking place today," she said. "Nothing has changed in that process."
"Frankly, we're ready for those things to go forward and come to their full completion and so that we can all move on," she said. "We're extremely confident that when this comes to conclusion, that everyone will continue to see what they've been seeing and we've been saying for the last 11 months. There was no collusion between the president and Russia."