"[FBI Director James Comey] himself has said he doesn’t know whether the emails ... are significant or not," Clinton told reporters in Iowa Friday evening. "I’m confident whatever they are will not change the conclusion reached in July. Therefore it’s imperative that the bureau explain this issue in question, whatever it is, without any delay."

Earlier Friday, Comey informed top members of Congress in a letter that the bureau had “learned of the existence of emails that appear to be pertinent to the investigation.”