What went wrong for Mitt Romney in Colorado?

Tuesday was a bad night for Mitt Romney.

He downplayed expectations going into the night, and the little polling that had been done suggested that he was likely to lose to Rick Santorum in the Minnesota caucuses and the Missouri primary (which, since it won't be used to select delegates, had only symbolic value).

But his loss in Colorado was a shocker.

Polls from Public Policy Polling showed him ahead by a comfortable 10 points in the state, and he won Colorado with 60 percent of the vote in 2008. Colorado even has a significant Mormon population – though far less than in Nevada, a state Mr. Romney won comfortably just a few days earlier – but it failed to help him much. Romney lost to Mr. Santorum by 5 points in Colorado, and was trounced in Missouri and Minnesota.

"Nobody saw this coming," says Kyle Saunders, a political scientist at Colorado State University, noting that the political betting market Intrade gave Romney a 97 percent chance of winning Colorado just before the caucuses. "I think there were some signs ... but everybody assumed that Romney's organization and advantages and money were going to carry the day for him."

So what went wrong for Romney in Colorado? Or, what did Rick Santorum do right? And what does it mean for the rest of the nomination battle?

First off, some caveats. Caucuses are not only notoriously hard to predict with polls, but they also represent a small fraction of the voters, typically the most energized and polarized wings of a party. Colorado's caucuses are closed – open only to registered Republicans – and so don't represent the views of the state's many independent voters.

In fact, in 2008, when Romney did so well in Colorado, it was in part because he appealed to those same voters who likely supported Santorum this year. Romney had positioned himself as the conservative alternative to John McCain; this time around, Romney was the mainstream candidate and the conservative faction of his party went for Santorum.

Turnout this year was low even for a caucus. On Tuesday night in Colorado, about 65,000 people voted – down from 2008, when more than 70,000 voted in the GOP caucuses, and only a small fraction of the state's Republican voters.

"In a caucus where something like 8 percent turnout is considered a huge number, pretty small differences can have an enormous influence on the results," says Seth Masket, a political scientist at the University of Denver. The fact that, on the eve of the caucuses, Santorum suddenly seemed to have a shot may have influenced some Coloradans to get out and vote for him, says Professor Masket.

And, in what now seems to be a mistake on Romney's part, Romney spent relatively little time or money in any of the three states that held contests on Tuesday. Santorum, on the other hand, focused heavily on all three – betting correctly that he would have a better shot there than in Florida or Nevada – and in the week before the caucuses spent a lot of time in Colorado's most conservative and evangelical counties. Clearly, his message connected with some of those voters.

Still, more than anything, the results Tuesday night speak to an enthusiasm gap for Romney that the candidate needs to take seriously. Santorum's supporters – who tend to be the voters, in places like Colorado Springs and the surrounding area, who identify most closely with his socially conservative values and message – were energized to get out to vote. Romney's were not.

In looking at the precinct data as it came in Tuesday night, New York Times pollster Nate Silver noted that turnout was much lower in Denver suburbs – where Romney likely has more support – than in other areas of the state where Santorum was beating him.

"We have repeatedly noted the pattern in which Mr. Romney's stronger states and counties have been associated with lower Republican turnout," Mr. Silver wrote Tuesday night. "In Colorado, where the demographics were reasonably favorable to Mr. Romney – he won 60 percent of the vote there in 2008 – it may have made the difference. Mr. Romney's stronger areas in the state were associated with turnout declines of about 20 percent. But turnout was steady or slightly up in places where Rick Santorum did well.

"Among other problems for Mr. Romney, this suggests that ... the caucus states could be problematic rather than advantageous to Mr. Romney, with his superior organization being outmatched by very conservative voters who have low levels of enthusiasm for him."

Romney may be relatively well positioned for the next contests – primaries, not caucuses, in Arizona and Michigan – and for Super Tuesday, where his big money and organization advantages will be especially useful. But caucus states will continue to be a factor (and some political analysts believe Hillary Clinton lost to President Obama in part because she underestimated their importance and his ability to perform well in them).

Most analysts believe the nomination will still likely go to Romney, but his loss in Colorado points to big weaknesses his campaign will have to address. One thing observers probably shouldn't do, however, is expect state voters in the general election to perform similarly. Colorado is likely to be a pivotal swing state in the general election, but voters then will be looking for something different than the caucus voters Tuesday night.

In Colorado, "Santorum isn’t going to be able to appeal to the one-third of the Colorado electorate who are unaffiliated as well as Romney is," says Professor Saunders at Colorado State University. "It puts Republicans in a bit of a situation. Did the Republican party shoot itself in the foot [Tuesday night] because of the results? I think Republicans will turn out even if Romney is the nominee, but there is definitely an enthusiasm gap for him."

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