Democratic presidential candidate Hillary Clinton meets Iowa voters at a rally in Cedar Rapids, Iowa on Saturday. (Melina Mara/The Washington Post)

Hillary Clinton played down news that emails passing through her private email server while she was secretary of state contained "top secret" information, saying it is "concerning" that the news broke three days before Monday's Iowa caucuses.

"This is very much like Benghazi," Clinton said on ABC's "This Week," referring to a heated political debate over her handling of the 2012 terrorist attacks. "The Republicans are going to continue to use it, beat up on me, I understand that, that's the way they are ... I think it's pretty clear they are grasping at straws."

The State Department acknowledged Friday that 22 emails spread across seven email chains contained "top secret" information. The messages were either sent or received by Clinton, whose campaign took the unusual step in response of criticizing the intelligence community for "overclassification run amok."

The revelation comes at a sensitive time for Clinton, who is running neck-and-neck with Sen. Bernie Sanders (I-Vt.) in Iowa. A Des Moines Register/Bloomberg poll released Saturday found the former secretary of state leading Sanders by only three percentage points, 45 to 42, ahead of Monday's caucuses.

With candidates vying neck-and-neck for support in Iowa, the Post's David Weigel walks through what it will take to win the Iowa Caucuses. (Alice Li/The Washington Post)

Interviewed Sunday about Clinton, Sanders called the email issue "very serious." Still, he said, there is a "legal process in place" for understanding what happened.

"I do not want to politicize that issue," Sanders said on CNN's "State of the Union." "That is not my style."

Clinton argued Sunday that the emails should be publicly released, chalking the controversy up to an "interagency dispute" over secrecy standards. She struck a confident note about her chances in Iowa.

"I've been subjected ... to years of scrutiny, and I'm still standing, talking to you, in the lead here in Iowa for the caucuses, and it's a very tough gauntlet to run," she said, adding that she feels "vetted," "ready" and "strong."