Three more states vote today, with Colorado and Minnesota holding caucuses and Missouri having its primary. Zero delegate are awarded as a result of any of these contests (at least directly), yet this could have an impact on the race going forward. Why? Because it represents Rick Santorum’s best chance to eclipse Newt Gingrich and emerge as Mitt Romney’s leading conservative challenger.

Santorum leads in Missouri, where Gingrich isn’t even on the ballot, and Minnesota. He is running second behind Romney in Colorado. Caveat: low-turnout caucuses are notoriously difficult to poll and the Democratic firm Public Policy Polling has done the only work in Minnesota that I’ve seen. Well organized campaigns are sometimes able to dramatically outperform their poll numbers and it’s hard for pollsters to know who will actually turn out.

That said, Santorum has been looking for his chance to become the anti-Romney and it is unlikely he will get a better one. Other things to watch: If Gingrich keeps losing can he keep going? Today is also another test of Ron Paul’s caucus strategy. Paul is polling competitively with Romney and Gingrich in Minnesota, where he will be able to turn out independents to vote for him.