Clinton campaign chairman John Podesta criticized FBI Director James Comey on Sunday for revealing a review of newly-discovered emails related to the agency's investigation into Hillary Clinton's use of a private server, noting that Comey could not even say if the emails contained significant information.

Podesta, appearing on CNN's State of the Union with Jake Tapper, called the letter released by Comey Friday "long on innuendo, short on facts" and said Comey appeared to be breaking with precedent by disclosing information about an ongoing investigation before determining if the newly-discovered emails provide any new insights.

"If they're not significant, they're not significant," Podesta said. He added that Comey "should have read them first" before making a bombshell announcement 11 days before the election.

"He might have taken the first step of actually having looked at them before he did this in the middle of a presidential campaign, so close to the voting," Podesta said. "This is something that has been tossed into the middle of the campaign. We would have preferred that that not happen, but now that it has happened, we would prefer that Mr. Comey come forward and explain why he took that unprecedented step."

Donald Trump tweeted Sunday that Democratic criticism of Comey is hypocritical.

Trump running mate Mike Pence praised the FBI's decision to review the emails, but sent an ambiguous message about how it might affect the election.

“I don’t think it alters the campaign at all,” Pence told Fox News Sunday. “What we already know here is troubling to the American people, and it’s convincing millions of Americans that Hillary Clinton is just a risky choice in this election.”

Democratic vice presidential nominee Tim Kaine called Comey's letter "extremely puzzling" and a "distraction."

In an interview with ABC News' George Stephanopoulos on This Week, Kaine said Comey's announcement of the review was a breach of Justice Department protocol because it happened close to an election and discussed an ongoing investigation.

Comey sent a letter to congressional leaders on Friday announcing that newly-discovered emails were being reviewed in connection with the investigation of Clinton's use of a private email server while secretary of state. The emails were found during a separate investigation of former Congressman Anthony Weiner, the estranged husband of Huma Abedin, a longtime Clinton aide and adviser.

"It is just extremely puzzling,” Kaine said. “Why would you release information that is so incomplete when you haven’t even seen the material yourself? Eleven days before an election, why would you talk about an ongoing investigation? I just have no way of understanding these actions. They’re completely unprecedented. And that’s why I think (Comey) owes the American public more information."

Kaine added that, "As far as we know now, Director Comey knows nothing about the content of these emails. We don’t know whether they’re to or from Hillary at all."

Podesta said Abedin has been fully cooperating with the FBI. He also said she remains on the campaign staff.

Trump campaign manager Kellyanne Conway praised Comey's decision to announce the review of the newly found emails.

"Hillary Clinton flouted the law and set up a private server so she could hide stuff from the public," Conway said.

Sen. Ron Johnson, R-Wis., chairman of the Senate Homeland Security and Governmental Affairs Committee, said, "I'm not praising James Comey."

"I think this investigation has been bungled from the start," the senator said on Fox News.

Contributing: David M. Jackson