Senator Tom Harkin says Republicans in the U.S. House are aiming at former Secretary of State Hillary Clinton with their new investigation of the 2012 attack in Benghazi that killed the U.S. Ambassador to Libya and three other Americans.

“This is designed to throw some dirt in the face of Hillary Clinton. That’s what this is all about. That’s what they want to do. They want to try to pin what happened at Benghazi on Clinton because they’re afraid she’s going to get the nomination and they don’t know that they can beat her in 2016,” Harkin told Iowa reporters on a telephone conference call early this afternoon. “That’s what this is all about.”

Republicans in the House point to recently-released emails suggesting Obama administration officials were concerned with protecting the president’s image in the days immediately after the attack. Getting better intelligence in the region seems like an important goal, according to Harkin.

“Look, I’m not an expert on Benghazi — I’d be the first to admit, but everything that I’ve followed and the briefings that I’ve had in the past seem to indicate that everything that really that we know happened we know about,” Harkin said. “I mean, it’s all been made public. It’s been thoroughly investigated and so I don’t know what any new investigation is going to uncover.”

The House is set to vote this evening on a plan that would establish a “select committee” to investigate the attack on the diplomatic outpost in Libya. House Democrats are considering a boycott of the committee. Harkin said his fellow Democrats in the House should participate in the hearings.

“Why not participate? We know what the facts are,” Harkin said. “I mean it seems to me it’s always good to have someone there to point out if the ‘investigation’ starts going in the wrong direction or they start to get too political, it probably would be nice to have someone pointing out that it is political.”

AUDIO of Ed Tibbetts of The Quad City Times asking Harkin about the issue, 3:24

Back in 1992, Harkin ended his presidential campaign in March and immediately endorsed Bill Clinton. In 2008, Harkin did not endorse a candidate before the Iowa Caucuses, but Harkin’s wife, Ruth, publicly backed Hillary Clinton and campaigned with her throughout the state.