In Arkansas, which Mr. Romney carried by 23.7%, Mark Pryor would be hard-pressed if freshman Rep. Tom Cotton, an Iraq and Afghan war vet, runs.

WSJ: Rove: The GOP Sets Its Sights on the Senate in 2014

"He thought what was more important was that deficits fall below growth as a percentage of GDP -- certainly a laudable goal, but I think the federal government, like any business or any family, needs to work towards a balanced budget, " Rep. Tom Cotton, R-Arkansas, said afterward.

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