Republican presidential candidate Donald Trump suggested Mrs Hillary Clinton was being "protected by a rigged system" after FBI director James Comey cleared her name over the use of a private e-mail server, while reminding voters about the thorny issue as they head to the polls today.
Writing to lawmakers on Sunday, Mr Comey said the Federal Bureau of Investigation (FBI) has not altered its initial stance that Mrs Clinton should not face criminal charges over her handling of classified information while she was secretary of state. "Based on our review, we have not changed our conclusions that we expressed in July with respect to Secretary Clinton," he wrote.
But many Republicans were reluctant to accept the FBI's latest assessment of the case.
Mr Trump, who had previously praised the FBI for reopening the investigation, reverted to criticising the agency while at a Michigan rally on Sunday.
"You can't review 650,000 new e-mails in eight days. You can't do it, folks," he said. "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 Nov 8."
Sunday's development also seems to have given Mr Trump cause to rekindle the rhetoric that the system is rigged against him.
NO NEW CONCLUSIONS
We reviewed all of the communications that were to or from Hillary Clinton while she was Secretary of State. Based on our review, we have not changed our conclusions that we expressed in July.
FBI DIRECTOR JAMES COMEY
GLAD THAT IT'S OVER
We're glad this issue is resolved but for the record, this could easily have been learnt before 1st letter was sent.
CLINTON SPOKESMAN BRIAN FALLON, on Twitter.
IT'S UP TO THE PEOPLE NOW
Hillary Clinton is guilty. She knows it, the FBI knows it... and now it's up to the American people to deliver justice at the ballot box on Nov 8.
MR DONALD TRUMP, at a rally after the FBI news broke.
At a rally in Minnesota, he said: "You have to understand it's a rigged system and she's protected."
Mr Comey revealed that the FBI had reviewed all of the new e-mails - which had surfaced in an unrelated case - that were "to or from Hillary Clinton while she was Secretary of State", effectively closing the case for the second time this year.
This announcement came just two days before Americans vote for the next US president and nine days after Mr Comey initially announced that the FBI was reopening the case - a move that severely hurt Mrs Clinton's campaign in the polls.
According to a polling average by political website RealClearPolitics, Mrs Clinton's lead over Mr Trump dipped to a low of 1.9 percentage points in the days after Mr Comey's initial announcement. Her lead over Mr Trump now stands at 2.2 percentage points.
Republican vice-presidential nominee Mike Pence also disagreed with the outcome of the review.
"Mishandling classified information is a crime," he said at a rally in 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."
Even House Speaker Paul Ryan - who has distanced himself from the Trump campaign after the release of a tape in which Mr Trump made lewd comments about women - also issued a statement underplaying the significance of Mr Comey's announcement.
"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," Mr Ryan said.
At the Clinton camp, the reaction was one of muted relief.
"We are glad that this matter is resolved," Mrs Clinton's communications director Jennifer Palmieri told reporters.
Mr Adam Schiff, the top Democrat in the House Intelligence Committee, said the announcement should put to rest the "irresponsible speculation indulged in by the Trump campaign and others".
He urged voters to make their decisions based on the merits of each candidate.
"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," said Mr Schiff.