"FILE - In this Feb. 22, 2012, file photo Republican presidential candidates, former Massachusetts Gov. Mitt Romney, right, and former Pennsylvania Sen. Rick Santorum, argue a point during a Republican presidential debate in Mesa, Ariz, during which Santorum confronted Romney about ""Obamacare"".  All four GOP candidates now promise to repeal ""Obamacare,"" with Santorum calling it ""the death knell for freedom."" Its model was a Massachusetts law signed by frontrunner Romney, when he was governor. (AP Photo/Jae C. Hong, File)"
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