WASHINGTON - A resurgent Rick Santorum won Minnesota's Republican presidential caucuses with ease Tuesday night and was declared the victor in Colorado as well, a stunning sweep that raised fresh questions about front-runner Mitt Romney's appeal among the ardent conservatives at the core of the party's political base.

Santorum triumphed, as well, in a nonbinding Missouri primary that was worth bragging rights but no delegates.

"Conservatism is alive and well in Missouri and Minnesota," the jubilant former Pennsylvania senator told cheering supporters in St. Charles, Mo. Challenging both his GOP rival and the Democratic president, he declared that on issues ranging from health care to "Wall Street bailouts, Mitt Romney has the same positions as Barack Obama."

Returns from 83 percent of Minnesota's precincts showed Santorum with 45 percent support, Texas Rep. Ron Paul with 27 percent and Romney - who won the state in his first try for the nomination four years ago - with 17 percent. Former House Speaker Newt Gingrich trailed with 11 percent.

In Colorado, the state party chairman, Ryan Call, said Santorum was the winner in a long, slow count.

He spoke as returns from 79 percent of the precincts showed the former Pennsylvania senator with 38 percent support to 35 percent for Romney. Gingrich led Paul for third place, although both men had 13 percent of the vote.