Clinton campaign chair John Podesta on Sunday railed against Director James Comey's revelation that the FBI is reviewing additional emails linked to Hillary Clinton's private server.

"Mr. Comey really needs to come forward and explain why he took this unprecedented step, particularly when he said himself in the letter to the Hill that these may not even be significant," Podesta said on CNN's "State of the Union."

Podesta contrasted Clinton and Donald Trump styles, arguing that she has learned from the fallout over her private server user whereas the GOP candidate often refused to acknowledge mistakes or apologize for controversial behavior.

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"[Clinton] said she wouldn't do it over again," Podesta said. "It's very clear that this has been an issue through the course of this campaign. I think she obviously would like to take that decision back, but she's learned from it ... in contrast to our opponent who never seems to learn from his mistakes and keeps repeating them and doubling down on them."

Podesta also defended Clinton aide Huma Abedin, saying, "I think it's clear that she complied to the best of her abilities, turned everything over that she had in her possession. I don't know anything more than the speculation that's running wild in the press now what this is about," Podesta said.

Federal law enforcement officials told NBC News that emails being looked at were found during a criminal probe into Abedin's estranged husband, former congressman Anthony Weiner, who has been accused of sending sexual text messages to an underage girl.

Podesta also called on the FBI to look into his own hacked emails.

"A Trump confidante Roger Stone who bragged about being in touch with (WikiLeaks') Julian Assange and talked about the fact that they were going to come after me," Podesta said. "He did that back in August. What the government has learned about the interactions between Assange and the Russians, it seems clear that the Russians were the ones who did the initial hack. How they got to Wikileaks, what the relationship was with Roger Stone? ... Maybe Jim Comey, if he thinks it's important, he will come out and let us know in the next nine days."