Jubilant Santorum wins Minnesota, leads in Colo.

WASHINGTON — A resurgent Rick Santorum won Minnesota's Republican presidential caucuses with ease Tuesday night and reached for victory in Colorado, raising 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 74 percent of Minnesota's precincts showed Santorum with 45 percent support, Texas Rep. 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.

Romney prevailed in both Minnesota and Colorado in 2008, the first time he ran for the nomination, but the GOP has become more conservative in both states since then under the influence of tea party activists. Nor was he backed by the overwhelming advantage in television advertising, including fiercely negative attacks on his rivals, that had helped him in other states this year.

In Colorado, with returns counted from 32 percent of the precincts, Santorum had 43 percent support with Romney at 28 percent, Gingrich at 15 and Paul trailing with 13 percent.

Romney showed no sign of disappointment in remarks to supporters.

"This was a good night for Rick Santorum. I want to congratulate Sen. Santorum, but I expect to become the nominee with your help," he told supporters in Denver.

If the night was good for Santorum, it was grim for Gingrich, who made scant effort in any of the states that voted during the day. He ran far off the pace in both caucus states, forced to watch from the sidelines while Santorum boasted of being the candidate with conservative appeal.

There were 37 Republican National Convention delegates at stake in Minnesota and 33 more in Colorado, and together, they accounted for the largest one-day combined total so far in the race for the GOP nomination.