Nevada caucused over the weekend, and tomorrow Republicans in Colorado and Minnesota get their chance to caucus, while Missouri holds a non-binding “beauty contest” primary unrelated to delegate selection. If you think Mitt Romney has basically wrapped up the nomination, you might be inclined to believe that there’s no reason to pay attention to these events.

Hre’s why they do matter.

What’s at stake: The extent to which Romney has to continue to engage in the nomination fight. If he extends his streak of landslide wins on Tuesday, that’s going to make it that much easier for Romney to increasingly ignore his opponents — and, in fact, to ignore Republican voters. Indeed, these sorts of things can turn positive for the nominee. It’s possible that with Ron Paul and (probably) Newt Gingrich staying in the race for the long haul that Romney will be able to use the long series of primaries through June to provide almost weekly reminders that he’s (1) a winner and (2) a moderate and nothing like the crazies in the Republican Party.

However, none of that works if Romney slips up frequently. Losing the occasional state, or even having close scares, isn’t going to seriously threaten his grip on the nomination. But it certainly could force him to stay engaged in the primaries, and not in the general election. That’s bad for him if he’s forced to re-emphasize positions which are necessary to win the nomination but are unpopular with swing voters (such as Paul Ryan’s House budget). But it’s even bad for him if it further delays the time when he’s able to move his rhetoric from things that play well with the GOP base (apology tour!) to things that will appeal to the broader electorate.

The wrinkle tomorrow is that it’s probably Rick Santorum’s last stand, and Santorum — who has some decent poll numbers in tomorrow’s states — is ultimately a bigger headache for Romney than Newt Gingrich or Ron Paul. So that means there is something at stake tomorrow after all: if Romney can sweep the three contests, it’s hard to see Santorum continuing in the race, and that would be a big step towards the general election for Romney.

On the other hand, should Santorum have a good day, he’ll stay in through Super Tuesday and it’s even plausible that Romney will be forced to stay engaged well past the first week of March. And for Mitt, that could mean many more weeks of pandering to Republican primary voters.