Dennis Moore's tea party had earlier endorsed Herman Cain, but when he dropped out, Moore hesitated about jumping on the Santorum bandwagon because "we can't afford to put a weaker candidate against Barack Obama," he said. "Mitt Romney is the only one who can win."

Moore, who helped organize the first tea party convention in Michigan in 2009, added: "It's pragmatic politics of the possible, and that's very unpopular with tea party folks."