As the FBI obtained a warrant to start searching a collection of emails that may be relevant to the investigation of Hillary Clinton’s use of a private email server when she served as secretary of state, Democrats suggested the timing and announcement of the probe were politically motivated.
FBI investigators knew weeks ago that emails found in a separate investigation may be related to the Clinton email case, but did not reveal their discovery until 11 days before the presidential election.
FBI Director James Comey sent a letter to congressional leaders Friday informing them of the development. Comey said in his notification to Congress that investigators didn’t know if the discovery was significant, as the material had not yet been reviewed.
Comey accused of politicizing investigation
Senate Minority Leader Harry Reid on Sunday suggested Comey was using his position to influence the election and, in doing so, may have broken the law.
In a letter, Reid also charged that Comey ignored requests to release "explosive information" the senator believes the FBI has about ties between Republican candidate Donald Trump’s campaign and Russia.
"By contrast, as soon as you came into possession of the slightest innuendo related to Secretary Clinton, you rushed to publicize it in the most negative light possible," Reid wrote.
Former U.S. Attorney General Eric Holder and nearly 100 former senior Justice Department officials and prosecutors also expressed concern in a letter about Comey's announcement and its timing so close to election day.
"We cannot recall a prior instance where a senior Justice Department official – Republican or Democrat – has, on the eve of a major election, issued a public statement where the mere disclosure of information may impact the election's outcome, yet the official acknowledges the information to be examined may not be significant or new."
WATCH: Clinton on Comey's decision
The letter says the American people deserve to have all of the information released so they can get a "full and complete picture" of the situation.
Trump’s running mate, Indiana Governor Mike Pence, defended Comey’s decision to notify Congress, calling it "an example of real leadership."
Comey on Friday sent a memo to FBI employees explaining his decision to update congressional leaders. While acknowledging that "we don’t ordinarily tell Congress about ongoing investigations," Comey said he felt obligated to do so because he had testified before Congress that the investigation was completed. He also said he believed "it would be misleading to the American people were we not to supplement the record."
Trump compares emails to Watergate
Trump pounced on the latest FBI revelation as more evidence confirming one of his central campaign themes: that Clinton is untrustworthy.
Campaigning in New Mexico on Sunday, Trump said the Clinton email investigation was "the single biggest scandal since Watergate."
"A vote for Hillary is a vote to surrender our government to public corruption, graft, cronyism that threatens the survival of our Constitution itself," he said at a campaign stop Saturday in Colorado.
WATCH: Trump on Clinton email scandal
"There’s this constant cloud of corruption that follows Hillary Clinton around," said Trump’s campaign manager, Kellyanne Conway, appearing on "This Week," one of the televised Sunday political talk shows. "And for the FBI to make this remarkable move 11 days before the election means there must be something there."
Emails discovered during sexting investigation
The latest emails were uncovered in a separate FBI investigation of former U.S. Representative Anthony Weiner, the estranged husband of top Clinton aide Huma Abedin.
Weiner is accused of exchanging sexually explicit emails with a 15-year-old girl. A separate batch of emails that the FBI believes may be related to the Clinton probe was found on a computer allegedly shared by Weiner and Abedin.
Weiner is a former congressman who resigned in 2011 after admitting he had exchanged explicit photographs and text messages with several women. He later ran for mayor of New York City, only to see that campaign spoiled by evidence that he was again engaging in sexting.
After federal authorities began investigating Weiner for allegedly exchanging explicit messages with an underage girl, he and Abedin separated.
WATCH: Furor Builds Over FBI Email Bombshell
Revelation ‘puzzles’ Democrats
The Clinton campaign and Democrats were delighted when Comey said in July that the FBI's investigation into Clinton's "sloppy" handling of emails when she was secretary of state would be closed with no criminal charges.
But the possibility that the probe could be reopened has got Democrats perplexed.
“It’s pretty strange to put something like that out, with such little information, right before an election,” Clinton said.
“It’s just extremely puzzling,” said vice presidential nominee Tim Kaine, also appearing on "This Week." "I just have no way of understanding these actions. They are completely unprecedented."
In an interview with CBS's "Face the Nation," taped before the Comey announcement and broadcast Sunday, Vice President Joe Biden said Hillary Clinton faces what he calls a "double standard" when it comes to trustworthiness.
"Hillary said herself... 'Look, I'm not that good a candidate,'... and a lot of it has to do with personal style. She is more measured and she makes fewer mistakes than I make or most people I know. It doesn't go to her integrity or honesty. It goes to her style."
Millions of Americans already have cast early ballots in states across the country. What effect the FBI announcement might have on turnout is unclear, but polls showed a tightening race between Clinton and Trump even before Friday’s announcement.