Eleven days before Americans determine the winner of a presidential contest already laden with multiple scandals, the political landscape looked even muddier on Friday with the latest October surprise.

The revelation, immediately greeted by Donald Trump as a political gift, emerged in the form of a letter from FBI Director James Comey to lawmakers. He advised the legislative branch that “emails that appear to be pertinent” to the investigation of Hillary Clinton’s personal email server were uncovered “in connection with an unrelated case,” and were under FBI review “to determine whether they contain classified information, as well as to assess their importance to our investigation.”

Comey’s three-paragraph announcement, which offered no clues about the significance of the newly discovered emails or the time needed to draw conclusions about what they contain, ignited speculation about how the electorate will greet the information. It also raised speculation about whether Comey sought to sway an election by informing Congress he wanted “to supplement” his July testimony that the Clinton email probe was “completed.”

Comey is a Republican whose 10-year term began in 2013.

Before Friday, data gleaned from public polling and voter focus groups suggested Clinton was on a path to becoming president after Nov. 8. Many who said they already filled out ballots for Clinton or intended to do so also indicated they disapproved of the former secretary of state’s decision to conduct government business using a private email system. Clinton has said her reliance on a private email system was “a mistake.”

It was unclear whether Friday’s news would shift the dynamics of the race by depressing turnout for Clinton or ginning up support for Trump, who has called the former secretary of state “crooked” and argued she skated out of culpability for breaches of the law. Clinton is viewed by majorities of Americans as dishonest and untrustworthy, and Trump has said for weeks that if his rival wins, the election will have been rigged.

Clinton, responding to the events late Friday following a rally in Iowa, said she was in the dark about what the FBI had uncovered, adding, “It’s imperative that the [FBI] explain this issue in question, whatever it is, without any delay ... Let’s get it out.” She implied that Comey’s letter was partisan, emphasizing that he sent it to Republican committee chairmen, and not to Democratic ranking members.

President Obama, campaigning for Clinton in Florida, was silent about the matter. The president learned of the FBI letter from the news media, his spokesman said.

Trump, who campaigned Friday in New Hampshire and Maine, said the FBI letter bolstered his view that investigators were wrong to conclude in the summer that Clinton was innocent of federal crimes. “Hillary Clinton’s corruption is on a scale we have never seen before. We must not let her take her criminal scheme into the Oval Office,” he said.

Republican leaders joined him in criticizing Clinton.

“Yet again, Hillary Clinton has nobody but herself to blame,” House Speaker Paul Ryan said in a statement. “She was entrusted with some of our nation’s most important secrets, and she betrayed that trust by carelessly mishandling highly classified information. This decision, long overdue, is the result of her reckless use of a private email server, and her refusal to be forthcoming with federal investigators. I renew my call for the Director of National Intelligence to suspend all classified briefings for Secretary Clinton until this matter is fully resolved.”

In July, Comey announced the FBI would not recommend any federal charges against the former secretary of state or her top aides related to her use of a private email server at the State Department. Comey determined weeks before the Democratic National Convention that Clinton had been “extremely careless,” but he said the FBI found no intent by the former secretary of state to break federal laws.

Anonymous law enforcement officials, cited by numerous media outlets Friday, described the FBI’s newly uncovered materials as communications recovered from devices maintained by Clinton senior campaign aide Huma Abedin, the estranged wife of former New York congressman Anthony Weiner.

The FBI is investigating allegations that Weiner sent sexually inappropriate communications to a 15-year-old girl in North Carolina, and in that context the FBI reportedly has searched accounts and devices belonging to Abedin and Weiner.

Abedin, who began working with Clinton as an intern and is described as like a second daughter to the Democratic nominee, was with the candidate in Iowa on Friday.

Libertarian presidential candidate Gary Johnson, reacting to the FBI letter, said voters should rethink support for both Clinton and Trump. “I think there is an honorable alternative, that happens to be me and [running mate] Bill Weld,” he said on CNN.

“Obviously, the FBI didn’t do this lightly,” he said. “There has to be something there.”

Johnson said voters ran the risk of “a potential president-elect” laboring under a criminal investigation or potential special prosecutor. “It’s a mess,” he added. “And Trump is toast.”

Clinton’s use of a private email account and her reliance on private servers and multiple communications devices first came to light in 2015 as a byproduct of New York Times reporting about State Department materials demanded by Congress as part of probes tied to the deaths of four Americans in Benghazi, Libya, in 2012.

Congress, under Republican control, launched investigations into Clinton’s emails, which in turn spawned Freedom of Information Act litigation by media organizations and outside groups in the courts seeking release of the communications. The email controversy eventually triggered the FBI’s investigation into whether classified information traveled from Clinton or to others using unsecured systems after she opted not to use the state.gov system. The FBI obtained Clinton’s servers and recovered some emails that her employees believed they had destroyed.

Questions about Clinton’s emails have dogged her since the launch of her second presidential bid last year. The controversy is separate from the more recent WikiLeaks disclosures of hacked email communications from Podesta’s Gmail account, which the Clinton campaign blames on Russian government backing behind Trump’s campaign.