FBI Director James Comey. Alex Wong/Getty Images FBI Director James Comey told Congress on Sunday that a review of new emails found in relation to the bureau's investigation into Hillary Clinton's use of a private email server had not yielded any reason for charges against the Democratic presidential nominee.

"Based on our review, we have not changed our conclusions that we expressed in July with respect to Secretary Clinton," Comey wrote in a short letter.

In July, Comey characterized Clinton and her team of being "extremely careless" while handling classified information during Clinton's time as secretary of state but said no "reasonable prosecutor" would move forward with a case.

But a little more than a week ago, Comey stunned the political world when he announced that the FBI had reactivated its investigation into Clinton after discovering new emails "pertinent to the investigation."

The emails were found on a laptop used by Anthony Weiner, the estranged husband of top Clinton aide Huma Abedin. Weiner is under federal investigation related to allegations he sexted with a minor.

The FBI director told Congress on Sunday that since the announcement his team had been "working around the clock" to process the newly discovered emails.

"We reviewed all communications that were to or from Hillary Clinton while she served as secretary of state," Comey wrote.

After doing so, the bureau determined that there was no reason to change its July conclusion.

Brian Fallon, the press secretary for Clinton, wrote on Twitter that the campaign was "always confident nothing would cause the July decision to be revisited."

"Now Director Comey has confirmed it," Fallon added.

Donald Trump, the Republican presidential nominee, did not immediately address the news during a campaign stop in Minnesota on Sunday afternoon, but his campaign manager, Kellyanne Conway, appeared on MSNBC and insisted the campaign had not made the FBI investigation a significant part of its campaign.

"We have not made this a centerpiece of our messaging, although we are asked about it constantly," she said on the network. "This has not been front and center of our campaign."

Despite Conway's claims, Trump had been using the latest FBI investigation to attack Clinton. In the past week, he and his surrogates used every opportunity they got to suggest the investigation would ultimately lead to an indictment that could thrust the country into an unprecedented constitutional crisis should Clinton be elected.

The message appeared to have been resonating with some voters. Polls have considerably tightened in recent days, both nationally and in battleground states.

With just two days left in the race, news Clinton had again been cleared of wrongdoing could not have come much later for her and her campaign.