Ed asked earlier whether today could be a big day for Rick Santorum. The question could just as easily be phrased: Could today be Mitt Romney’s small day? The Romney campaign itself senses that it’s likely to face at least one loss tonight — probably in Missouri, probably to Santorum — and has sought to tamp down expectations accordingly.

In a memo released by the campaign this morning, Romney political director Rich Beeson reminded readers that the contests today produce no delegates to the nominating convention.

“[T]here is no way for any nominee to win first place in every single contest — John McCain lost 19 states in 2008, and we expect our opponents to notch a few wins too,” the second paragraph of the memo states.

The remainder of the document — topped with the subject line “The Road Ahead — A Reality Check” — bears no hint of nervousness, though. With an emphasis on Romney’s organizational strength, Beeson outlines the former Massachusetts governor’s path to the nomination:

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.

In contrast, Governor Romney will be competing across the country and collecting delegates in state after state, even if other candidates pick up some wins. This is exactly the sort of methodical, long-haul campaign we planned for, and we are well on the way to victory.

That Romney has begun to take notice of Rick Santorum through surrogates like Tim Pawlenty shows that Romney still sees Santorum as a threat, especially in the middle states — but the overall thrust of the memo underscores a reality about presidential campaigns that is easy to forget in the excitement of debates and early states: Organization does matter, and Romney — alone of the current candidates — has been running for president for at least four years. A drawn-out race will favor him, and, in the end, each candidate’s delegate count does matter more than any symbolic show of support in Iowa, Missouri or elsewhere. Santorum stands a very real chance of unseating Newt Gingrich as the leading not-Romney today — but Romney is still the only Romney. That is, he’s still the only candidate who has been the frontrunner more often than not. Beeson is right: Romney can afford to lose one or two states today, no sweat. At this point, a small day for Romney is a big day for Santorum or Gingrich — in both senses of that sentence. What Santorum or Gingrich have to hype, Romney can do with or without. Iowa and South Carolina aside, might Mitt Romney be inevitable after all?