CEDAR RAPIDS, Iowa (AP) — A new shock hit Hillary Clinton's campaign Friday in the unpredictable and often unbelievable presidential race: The FBI is looking into whether there was classified information on a device belonging to the estranged husband of one of her closest aides.

Adding to the drama of the stunning revelation: The FBI uncovered the emails during a sexting investigation of Anthony Weiner, the disgraced ex-congressman who is separated from longtime Clinton aide Huma Abedin.

The news arrived with Clinton holding a solid advantage in the presidential race. Early voting has been underway for weeks, and she has a steady lead in preference polls. But the development all but ensures that, even should she win the White House, the Democrat and several of her closest aides would celebrate a victory a under a cloud of investigation.

It was a day that thrilled Republicans eager to change the trajectory of the race, none more so than GOP nominee Donald Trump.

"Hillary Clinton's corruption is on a scale we have never seen before," Trump said while campaigning in battleground New Hampshire. "We must not let her take her criminal scheme into the Oval Office."

Democrats, still confident Clinton will prevail in 11 days, were enraged by the decision of FBI Director James Comey to disclose the existence of the fresh investigation in a vaguely worded letter to several congressional leaders.

It wasn't until hours later that word emerged that the source of the new emails was Weiner, the former congressman under investigation for sending sexually explicit text messages to a teenage girl.

"Director Comey admits 'the FBI cannot yet assess whether or not this material may be significant,'" said California Sen. Dianne Feinstein. She added, accusingly, "The FBI has a history of extreme caution near Election Day so as not to influence the results. Today's break from that tradition is appalling."

It also it reignited persistent worries among Democrats that electing the former first lady will restart a cycle of scandal and investigation that could rival the final portion of her husband's term in office.

Congressional Republicans have already promised years of investigations into Clinton's private email system. And that's only one of the email-related controversies facing her. The tens of thousands of confidential emails from Clinton campaign insiders that were hacked — she and the government say by Russia — and then released by WikiLeaks have provided a steady stream of questions about her policy positions, personnel choices and ties with her husband's sprawling charitable network and post-presidential pursuits.

The Clinton campaign demanded more information about the FBI's unexpected announcement, with Clinton campaign chairman John Podesta saying in a statement that Comey "owes it to the American people to immediately provide the full details of what he is now examining."

Clinton's running mate, Tim Kaine, said the vague FBI statement just 11 days before the election, with details leaking out to the news media, "is very troubling." He, too, called for a quick, full accounting.

In his Friday letter to congressional leaders, Comey wrote only that new emails have emerged, prompting the agency to "take appropriate investigative steps" to review the information that may be pertinent to its previously closed investigation into Clinton private email system.

The FBI ended that investigation in July without filing charges, although Comey said then Clinton and her aides had been "extremely careless" in using the system for communications about government business.

The agency, which did not respond to questions about Comey's letter and did not lay out a timeline for the review, is also investigating the recent hacks of Podesta's emails.

For her part, Clinton remained silent, ignoring shouted questions from reporters and not addressing the subject at her public events in Iowa. Flying on her campaign plane when the news broke, she was traveling with Abedin, the estranged wife of Weiner.

As Clinton and her campaign have been pounded by allegations and embarrassing revelations related to the hacked emails, they've largely avoided engaging in the details. Instead, they've focused on blaming the Russians.

"These are illegally stolen documents," Clinton campaign manager Robby Mook said on her campaign plane. "We're not going to spend our campaign fighting back what the Russians want this to be about."

That may be because Clinton hasn't yet felt the political pressure. Recent surveys show her retaining her lead in national polls and making gains in some swing states. In fact, her campaign announced plans to hold a rally in Arizona next Wednesday, a traditionally red state put in play by Trump's deep unpopularity among minority voters, Mormons and business leaders.

To the frustration of many in his party, Trump has struggled to consistently drive an attack against Clinton, often turning to personal denunciations of private citizens he feels have wronged him, like the Gold Star family of Captain Humayun Khan, a Muslim-American soldier killed in action.

That may be changing: He quickly pounced on the email news, seeing an opportunity to press the argument he's long tried to make against Clinton: that she thinks she's above the law and that she put U.S. security at risk by using her personal email.

After weeks of declaring the race "rigged" in favor of his opponent, he declared Friday he has "great respect" for the FBI and the Department of Justice, now that they are "willing to have the courage to right the horrible mistake that they made" in concluding the investigation earlier.

White House spokesman Eric Schultz urged the FBI to "follow the facts, wherever they lead." President Barack Obama plans to travel to support Clinton nearly every day that's left in the campaign.

"He's going to be proud to support her from now until Election Day," Schultz said.

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Associated Press writers Julie Pace, Steve Peoples, Julie Bykowicz, Jill Colvin, Will Weissert and Josh Lederman contributed to this report.

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