The Minnesota Republican caucus has been called for Rick Santorum, giving the former Pennsylvania senator his second win on Tuesday after a huge victory in the Missouri primary.

By winning two states in one night, Santorum has rocketed from being a candidate who many expected to see leave the presidential primary race to who can now cast himself as one with significant staying power among socially conservative voters.

While Santorum's win in Missouri was purely symbolic (he will gain no delegates with his victory there), Minnesota has no less than 40 delegates for the taking.

According to The New York Times, Rick Santorum is even leading in early returns in the Colorado caucus, a state Mitt Romney was slated to win.

The Santorum Threat

Rick Santorum's double victory tonight is bad news for Mitt Romney, who had hoped to finally cement his place as the undisputed front-runner in the GOP presidential primary race.

The wins also come just a few days after Santorum's own humiliating fourth-place finish in Nevada, where Mitt Romney celebrated a hard-won but significant victory.

The Romney campaign began once again to turn its attention away from the other candidates to focus on attacking President Obama.

Signs that Santorum would be a threat, however, reappeared in the 24 hours before the polls closed.

Romney supporters like Tim Pawlenty, the former governor of Minnesota, suddenly pounced on Santorum. Pawlenty accused him of not being ready to be president, and argued that Santorum's assertion that he was the only real conservative in the race just isn't true.

Ron Paul Poised For Second Place

It would seem that the Romney campaign's fears were well-founded.

After seeing the specter of Newt Gingrich fade after the former Speaker's win in South Carolina, Romney now has to contend with a new threat to his chance to win the Republican nomination, one who can argue that neither Romney nor Gingrich are true conservatives when it comes to fiscal and social issues.

But Rick Santorum isn't the only candidate to come off well in the Minnesota caucus. Ron Paul is currently in second place with 27 percent of the vote, a good ten points above Mitt Romney.

The Texas congressman had hoped to win the caucus, but second place fits well in his strategy to gather delegates from caucus states as the candidates weave their way toward the Republican National Convention in August 2012.

Paul's Minnesota stumping, meanwhile, has not gone unnoticed. Nancy Hill, from Andover, told the AP it was her first time to a caucus, and that she was going to support the libertarian candidate.

Rod Garberson, meanwhile, showed up an hour early at a caucus where Ron Paul planned to make an appearance.

The Coon Rapids native told the AP he was so set on Paul as the Republican nominee that if another candidate won, he probably wouldn't vote in November.

I gotta tell you, this time I'm pretty well stuck on not supporting the party, Garberson said. Even if it means eight years of Obama and we all stand in bread lines for five hours for a sack of potatoes.