Mitt Romney’s struggles in the Colorado caucuses, where he finished a relatively close second to former Senator Rick Santorum, and his weaker showings in the Minnesota caucuses and the nonbinding Missouri primary, shouldn’t seriously derail his march to the Republican presidential nomination.

Despite Santorum’s strong showing on Tuesday, after his very poor showings in the more heavily contested South Carolina and Florida primaries, there is still no clear alternative to Romney; Santorum, Newt Gingrich, and Ron Paul are each taking a slice of the non-Romney vote. And caucuses and nonbinding primaries such as those on Tuesday tend to be more attractive to political activists, who are far more conservative than average voters. It’s not surprising that Romney didn’t do well in Minnesota and Missouri. But if Romney should feel the sting anywhere, it was in Colorado, where he competed heavily and spent money to organize supporters, and still came up short.