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Illinois Republicans are trying to make MoveOn.org’s endorsement a liability for the Democratic nominee in the airtight race for President Obama’s former Senate seat.

After the liberal activist group backed Democrat Alexi Giannoulias, the Illinois Republican Party called on the recipient Monday to “explain” that support.

Though MoveOn.org has endorsed a number of congressional candidates this year without incident, the Illinois GOP is stirring up trouble by trying to link Giannoulias to the group’s infamous 2007 ad blasting Gen. David Petraeus as “General Betray Us.”

Illinois Republican Party Chairman Pat Brady said in a written statement that Giannoulias “must” explain to voters if he believes “it’s acceptable to publicly smear a national hero like General Petraeus.”

He called on congressional candidate Dan Seals to do the same. “Giannoulias and Seals’ sudden embrace of the farthest left fringes of the Democratic Party should be a major concern to independent voters,” Brady said.

The MoveOn ad drew fierce, bipartisan criticism in 2007 -- Congress voted at the time to formally condemn the full-page take-out in The New York Times. President Obama, whom MoveOn also endorsed, stuck with Petraeus after taking office and over the summer appointed him to lead U.S. forces in Afghanistan.

'The Illinois GOP did not cite any evidence to suggest Giannoulias supports MoveOn’s statements about Petraeus, other than a campaign e-mail in which Giannoulias thanked the organization and declared “you and I share so much in common.”

Giannoulias’ website suggested MoveOn had gravitated toward his pledge to reject federal lobbyist and corporate PAC contributions. Giannoulias’ campaign did not respond to a request for comment.

Republican Senate nominee Mark Kirk has faced his own "military" problem, acknowledging in May that he falsely claimed to have received the U.S. Navy's Intelligence Officer of the Year award. He had won a different award.

The Senate campaign in Illinois is among the closest in the nation. Polls taken over the past month show Kirk leading by 3-4 percentage points.

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