"Based on our review, we have not changed our conclusions that we expressed in July," Comey wrote in the new letter to congressional committee chairmen.
Comey dropped a bombshell on the presidential race last month when he sent a letter to Congress saying the FBI had discovered emails in a separate investigation that could be connected to the now-closed probe of whether Clinton mishandled classified information. The move infuriated Democrats and emboldened Republican nominee Donald Trump.
It's impossible to know before results are tallied what impact Comey's actions -- first raising a vaguely worded red flag 11 days out, and then lowering it two days from the election -- will have on the contest. But the news could help Clinton put to rest a controversy that has dogged her in the 2016 race's closing days, helping Trump narrow a polling gap nationally and in key battleground states.
Trump assailed the FBI's handling of the matter, though he did not directly address Comey's announcement at a rally in Sterling Heights, Michigan.
"You can't review 650,000 new emails in eight days. You can't do it, folks," Trump said, adding, "Hillary Clinton is guilty. She knows it, the FBI knows it, the people know it, and now it's up to the American people to deliver justice at the ballot box on November 8."
Dianne Feinstein, the top Democrat on the Senate Select Committee on Intelligence, blasted Comey's handling of the review.
"Today's letter makes Director Comey's actions nine days ago even more troubling," Feinstein said in a statement. "There's no doubt that it created a false impression about the nature of the agency's inquiry."
She added: "The Justice Department needs to take a look at its procedures to prevent similar actions that could influence future elections."
'As fast as we could'
Comey's letter was the culmination of a fast-paced review of the newly discovered email, law enforcement sources said Sunday.
"We went through this as fast as we could," a senior law enforcement official told CNN, with another law enforcement official saying investigators worked "around the clock" to review the large volume of emails.
The FBI found the new emails as part of its separate investigation into a sexting incident by Anthony Weiner, the estranged husband of top Clinton aide Huma Abedin.
The thousands of new emails were mostly personal and duplicates of what had already been seen, law enforcement officials said in explaining how the conclusion was reached so quickly. The laptop which was found was about a decade old with lots of personal content on it not relevant to the investigation, according to one source.
The probe is considered over with regard to Clinton. Though with not all the deleted emails recovered and not all the devices in FBI's possession, it is always possible something else could turn up that would require more review.
There were some classified emails found, but law enforcement officials stressed the issue is not the classified information so much as proving intent. The sources would not specify if the the classified messages were new or duplicates of ones already reviewed, nor would would officials say how many there were and what levels at which they were classified.
"Keep in mind we are focused on intent," the official said. "We know there are classified materials, but that doesn't change the conclusion reached back in July."
As for others who were part of the probe, including Abedin, the FBI is still working on some remaining aspects of the review, including determining how the emails ended up on the laptop in the first place. Abedin's attorneys have said she doesn't know why these emails were there because this wasn't a computer she used.
The expectation remains that investigators will have to talk to Abedin again.
It isn't uncommon to come across new evidence after concluding a probe -- which is what happened here in October. Normally, investigators take a look to see if anything changes in their conclusions and it's not a controversial issue. This case isn't a normal case, given the election and the stakes.
DOJ informed of decision
Comey sent the letter as soon as possible, the senior law enforcement official said. He was "very careful" about how the letter was crafted given the sensitivities.
Attorney General Loretta Lynch was informed ahead of time that the FBI director was sending the updated letter to Congress informing them of that there would be no change in the FBI stance on Hillary Clinton, a Justice official told CNN on Sunday.
Lynch and Deputy Attorney General Sally Yates disagreed with Comey's earlier decision
to notify Congress. The attorney general backed Comey's move Sunday.
"Everyone is on the same page," the source said.
Since there is no change to the original findings, the Justice Department has no need to weigh in further, the official said.
"The Department of Justice and the FBI dedicated all necessary resources to conduct this review expeditiously," the Justice Department said in a brief statement released Sunday afternoon.
Campaigns weigh in
Clinton spokesman Brian Fallon said her campaign is validated in its belief that nothing would change.
"We were always confident nothing would cause the July decision to be revisited. Now Director Comey has confirmed it," he tweeted.
The Trump campaign quickly slammed Comey.
"We thought that Director Comey and the FBI were wrong when they made their initial recommendation in July, and we think that they're wrong now," Trump spokesman Jason Miller told CNN's Wolf Blitzer on "The Situation Room."
GOP vice presidential nominee Mike Pence sought to keep the pressure on Clinton.
"Mishandling classified information is a crime," he said at a rally in an airport hanger in Hickory, North Carolina. "Hillary Clinton said that she never sent or received any classified information and the director of the FBI told the Congress classified information was sent."
In Michigan, Trump called Clinton "the most corrupt person ever to seek the office of the presidency of the United States."
But the Republican nominee, who has expressed hope in the last week that the FBI's review of new emails might yield an indictment, emphasized to his supporters Sunday that Clinton is "protected" by powerful forces.
"Well, you have to understand it's a rigged system and she's protected," Trump said in Minnesota, though he offered no evidence to back up his theory.
'It opened a wound'
A senior Democrat close to Clinton's campaign told CNN that "it's impossible to fully undo the damage of the last nine days."
Internal campaign polling, the source said, found that some independents and Republican women fled Clinton after the original Comey announcement, robbing her of a constituency that she'd hoped would turn her contest with Trump into a blowout.
"It opened a wound that cannot be quickly healed," the Democrat said.
However, the Democrat called it a relief that the "matter is resolved" and said Clinton's campaign plans to "make everyone know about" Comey's Sunday letter.
Comey's last-minute announcement gives Clinton an opportunity for an I-told-you-so moment.
"We have seen Director Comey's latest letter to the Hill," said Jennifer Palmieri, Clinton's communications director, speaking with reporters after the news broke. "We are glad to see that he has found, as we were confident that he would, that he had confirmed the conclusions he reached in July and we are glad that this matter is resolved."
Trump and his allies have seized on that announcement, using it to claim Clinton was likely to face criminal charges.
"If she were to win, it would create an unprecedented constitutional crisis," Trump claimed Saturday night in Reno, Nevada. "In that situation we could very well have a sitting president under felony indictment and ultimately a criminal trial. It would grind government to a halt."
The political benefit for Trump has been that Republicans who'd been skeptical of their party's nominee have largely followed vice presidential nominee Mike Pence's calls to "come home" to the party -- finding Trump less objectionable than Clinton.
It's not just Trump's campaign that seized on Comey's actions. Down-ballot Republicans -- particularly Senate candidates who had been forced to answer for Trump's statements for months -- used the moment to change the topic, shifting to the more comfortable ground of attacking Clinton.
The last-minute Sunday move from Comey could also provide new fuel for Trump's claims of a "rigged" system -- allowing him to cast the FBI director's intervention in the presidential election in a new light.
Comey and the FBI went from Trump's scapegoat to the Republican nominee's hero, with Trump claiming Comey had redeemed himself just in time.
Newt Gingrich, a top Trump ally, tweeted "Comey must be under enormous political pressure to cave like this."
Dems, GOP react
House Speaker Paul Ryan dismissed the significance of Comey's latest letter.
"Regardless of this decision, the undisputed finding of the FBI's investigation is that Secretary Clinton put our nation's secrets at risk and in doing so compromised our national security," Ryan said in a statement. "Fortunately, the American people have the opportunity to ensure Secretary Clinton never gets her hands on classified information again."
Capitol Hill Democrats praised Comey's decision to release more information.
"While the original letter should never have been sent so close to an election, the expeditious review of these emails should put to rest -- once and for all -- the irresponsible speculation indulged in by the Trump campaign and others," Rep. Adam Schiff, the top Democrat on the House Intelligence Committee said. "Voters can now make their decision based on the merits, and that decision should be simple: it is the choice between a woman superbly qualified to be commander in chief, and a man patently unfit for office."
Republican National Committee Chairman Reince Priebus issued a statement saying, "None of this changes the fact that the FBI continues to investigate the Clinton Foundation for corruption involving her tenure as secretary of state. Hillary Clinton should never be president."