Today there are caucuses in Minnesota and Colorado and a beauty contest vote in Missouri (no delegates are affected, and a “real” caucus comes later in the primary calendar). In all likelihood, Mitt Romney isn’t going to win all or even most of these, although he may score an impressive victory in Colorado. His political director, Rich Beeson, is pre-spinning the contests with a memo. It reads, in part:

It is difficult to see what Governor Romney’s opponents can do to change the dynamics of the race in February. No delegates will be awarded on February 7 -- Colorado and Minnesota hold caucuses with nonbinding preference polls, and the Missouri primary is purely a beauty contest. Except for the Maine and Wyoming nonbinding caucuses running through February, the next contests are on February 28 in states where Governor Romney is strong. Arizona’s 29 delegates will be bound in a winner-take-all contest. Michigan, the state where Governor Romney grew up, binds 30 delegates.

The rules for the March states offer even less comfort to Governor Romney’s opponents. With so many states and territories voting, organization and resources are key. Ours is the only campaign to be active in all of these states, and we have the resources and organization to maximize delegate totals according to each state’s rules. Speaker Gingrich and Senator Santorum have no plan in the majority of the March states (although the Paul campaign has waged a systematic effort in a number of them). Governor Romney is the only candidate prepared to compete in simultaneous contests across the country.

You get the idea. The purpose of such a memo is two-fold — try to spin the media and discourage donors from giving to Rick Santorum. Romney’s message is essentially that no matter what happens tonight, the dynamics of the race won’t change. (“Speaker Gingrich’s and Senator Santorum’s campaigns have resource challenges. The remaining February states may not be kind to them, and their hopes for a comeback in March may be very difficult and based on an incomplete understanding of the delegate selection rules. Even ‘success’ in a few states will not mean collecting enough delegates to win the nomination.”) But is that right?

Certainly, Democrats, anti-Romney Republicans and the media will love a David-and-Goliath story and one more round of fisticuffs in which conservatives can make their case against Romney. Santorum, especially if he gives a high-energy victory speech tonight, will get a bump in the polls, some more donations and greater visibility in the media. The extent of the lift will depend, in part, on how wide the margins of victory are in the three states tonight and how the two candidates’ speeches are received.

From Romney’s standpoint, yet another challenger creates risks and opportunities. A challenge might further alienate the conservative base and point to concerns about his electability. But it also provides Romney with a chance, as he did in Florida, to show some toughness and to woo conservatives.

The main downside for Romney is that a spit-ball fight with another challenger may distract him from what he really needs to be doing: re-introducing his policy agenda, enhancing his tax reform proposal, and grilling President Obama on everything from Iran (why does he keep playing down the military option?) to the economy (is Jay Carney right that workers leaving the job market is a positive thing?)

Today, we’ll see if Santorum can present himself as a worthy challenger and if Romney can sustain the aura of inevitability.