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ABC News' Gregory Simmons and Shushannah Walshe report:

KENTWOOD, Michigan-It is not just Rick Santorum asking Democrats who support Barack Obama to help him defeat Mitt Romney in the Michigan primary. ABC News has learned of a  new robo-call sponsored by a Democratic political consultant that will go out at 5pm today and reminds voters they only  have three hours left to vote for the Republican candidate.

Santorum is engaging in his own cross over voter encouragement. His campaign is behind a robo-call urging Democrats to vote for him today too.

But the call sponsored by Democrats suggests a vote for Santorum would be valuable because it could embarrass Romney.

"Hi this is Tony Trupiano," the recorded voice in the Democratic robo-call narrates. "I just want to remind you, you only have three more hours to vote today. Of course you want to vote for Rick Santorum."

And then this: "And make sure that vote is an embarrassment for Mitt Romney."

Trupiano is a progressive talk show host in the state and the call is sponsored by a Michigan-based Democratic political consultant, Joe Disano

DiSano says the first robo-call, as reported by RealClearPolitics, reached 12,000 Democrats in Michigan

He believes as many as 14,000 Democrats will cross over and vote for Santorum, prolonging the primary process and further weakening the one-time frontrunner and hometown son.

"I do think this is going to make a difference," DiSano said.   "Roughly 200,000  people will vote today. This thing is neck and neck and if I can get these people to vote for Rick Santorum I think we can defeat Mitt Romney. He is so weak here the fact a religious fanatic like Rick Santorum can even come close shows how weak Mitt Romney is in his home state."

DiSano added that Mitt Romney's now-famous "Let Detroit Go Bankrupt" New York Times op-ed and opposition to the auto bailout are part of the reason he's engaging in this voter mischief.

"When he turned his back on us in the auto bailout, we remember that and now were turning our back on him," DiSano said.

Michigan has a long history of crossover voting and other electoral shenanigans because of their open primary where both Republicans and Democrats can participate.