The Republican presidential candidates are seizing on the "top secret" Hillary Clinton emails in the final weekend before the Iowa Caucus, trying to slow their top Democratic rival by arguing her mishandling of the message make her unfit to be president.
The intelligence community has deemed some of Clinton's emails "too damaging" to national security to release under any circumstances, a U.S. government official close to the ongoing review told Fox News.
Vermont Sen. Bernie Sanders, Clinton's top primary challenger, has declined to talk about the emails.
He trails Clinton by rough 5 points in Iowa but leads her by roughly 15 points in New Hampshire, which votes Feb. 9, according to the RealClearPolitics poll averaging.
Florida Sen. Marco Rubio, running third in most GOP polls behind Texas Sen. Ted Cruz, told an audience in Clinton, Iowa, that such sensitive emails being on Clinton's server is "not acceptable."