Mitt Romney, the front-runner for the nomination, finished a disappointing third place in Minnesota, behind Texas Rep. Ron Paul, and second in Missouri. Colorado, which Mr. Romney had expected to win fairly easily, was still too close to call late Tuesday night, and a Santorum win was a possibility.
Newt Gingrich, who had downplayed expectations going into Tuesday, had an even worse night, coming in last in Minnesota and likely a distant third place in Colorado. He was not on the ballot in Missouri.
Congressman Paul, who had hoped for a big boost from caucus states, notched a second-place finish in Minnesota, but was third in Missouri and performing poorly in Colorado.
Mr. Santorum's wins were, in some sense, symbolic. Missouri's primary was largely a "beauty contest," since the delegates will be chosen in caucuses in March. Minnesota's and Colorado's caucuses are also nonbinding, although there are actual delegates at stake and the results should help determine the selection of those delegates.
But they are still an important boost to his campaign at a pivotal moment, and seemed destined to prolong the nominating contest and keep Romney from sewing up the nomination quickly, at the least.
[ Video is no longer available. ]
"Your votes today were not just heard loud and wide across the states of Missouri and Minnesota, but they were heard loud and louder all across this country, and ... I suspect maybe in Massachusetts they were heard particularly loud tonight," said Santorum in a victory speech in St. Charles, Mo., in which he took aim at both President Obama and Romney – whom he attempted to cast as similar in their stances on health care, the environment, and Wall Street bailouts.
Santorum thanked the conservatives who gave him his win, noting that "tonight was a victory for the voices of our party, conservatives and tea party people," and tried to take on the mantle of nominee, saying, "I don’t stand here to claim to be the conservative alternative to mitt Romney, I stand here to be the conservative alternative to Barack Obama."
Notably, Santorum didn't mention Mr. Gingrich's name at all.
Romney's campaign sought to downplay the victories, noting that the contests matter little and that Romney didn't put any time or money into Missouri and relatively little into Minnesota.
In a speech to his supporters in Denver Tuesday night, Romney brushed off the losses, saying only, “This was a good night for Rick Santorum.”
“I want to congratulate Senator Santorum, we wish him the very best, we’ll keep campaigning down the road, but I expect to become the nominee with your help,” Romney added.
Indeed, Romney continued to speak as the front-runner and presumptive nominee, focusing the bulk of his speech on Obama’s record.
Still, the results in Minnesota and Missouri are not only a big boost for Santorum – who seems poised to bypass Gingrich as Romney's primary rival – but point to significant weaknesses for Romney in certain regions and demographics. While Romney performs well in the Northeast and West, he has so far struggled in the Midwest – where he has yet to get a win – and the South, as well as among conservative voters and those outside major metropolitan areas.
If Romney ends up losing Colorado, it will be an even bigger and more surprising loss.
The wins in Minnesota and Missouri were bigger than anticipated for Santorum. He won Missouri with about 55 percent of the vote – more than twice what Romney received (about 25 percent). He won many precincts that Romney won in 2008.
Fewer votes had been counted in Minnesota, but Santorum also seemed poised to win there by a very large margin, with more than twice as many votes as Romney, who was also well behind Paul.
Minnesota is particularly disappointing for Romney, given that he carried the state in 2008 with 41 percent of the vote – back when he positioned himself as the conservative alternative to John McCain.
If nothing else, Tuesday's contests underscored the unpredictable nature of this year's GOP nominating process, in which momentum rarely seems to carry over from one contest to the next.
"Mitt Romney's big wins in Nevada and Florida did not seem to do him much good tonight," wrote New York Times pollster Nate Silver in commentary Tuesday night, though he added that that lack of carryover from one state to the next may ultimately be to Romney's advantage, since "momentum from Rick Santorum's wins in Missouri and Minnesota could evaporate by the time that Arizona and Michigan vote on Feb. 28."
Another candidate – albeit from the other party – who is likely pleased by Tuesday's results: Barack Obama, whose campaign is hoping that the GOP nominating process drags on as long as possible.