(Yoon S. Byun/The Boston Globe via Getty Images)

Analysis

Mitt Romney's path to the Republican presidential nomination is being powered by victories very large - think Ohio, Michigan, and Florida - and very, very small.

If and when Romney locks down the GOP nod, this weekend's voting will mark a case in point as to how. Romney was decimated in the biggest contest held Saturday, in Kansas, with Rick Santorum securing an outright majority in a four-way field, and Romney struggling to hit 20 percent.

But Romney appears likely to walk away from the weekend with about as many delegates in his column, and possibly even more. Romney won overwhelmingly in the U.S. territories of Guam, the Northern Mariana Islands, and the Virgin Islands; add that to the final set of caucus contests in Wyoming, and Romney got to wash out his big loss in Kansas.

That means a handful of contests where turnout is rivaled by class presidency elections in midsize high schools may end up being responsible for selecting the party's nominee. To cite one example, 181 individuals attended the Guam Republican convention, according to the territory's party. (In Kansas, turnout topped 30,000.)

Wins like this weekend's did not happen by accident. Romney's was the only campaign to prepare for the long haul of the race with detailed legal and structural plans for how to win delegates in every obscure corner. That work is now paying off, as the battle for 1,144 Republican National Convention delegates slogs on.

Romney has 454 delegates secured, according to ABC's estimate, more than twice the 217 in Santorum's column. Newt Gingrich, with 109 delegates, and Ron Paul, at 48, lag far behind.

The fact that most states don't award all the delegates to a single winner makes it very difficult to amass enough delegates to clinch. But it makes it even harder for a lagging candidate to catch up.

Romney faces a fresh challenge Tuesday, with the big Southern states of Alabama and Mississippi showing potential of again ignoring the fact that there is one clear and away frontrunner. Santorum or even Newt Gingrich could walk away with victories.

But in Romney's back pocket are lower-profile caucuses that same day, held in Hawaii and American Samoa. They account for only 29 of the day's 119 delegates at stake. But when you factor in proportional delegate rules in Alabama and Mississippi that make shutouts unlikely, Romney may once again walk away the day's winner.

Thus, even in a remarkably difficult string of contests, Romney is not giving up major ground, and may even be padding his delegate lead. That's why it's so difficult for Santorum or anyone else to catch up, and why Romney remains almost certain to win the party's nomination.

Romney's team is confident because the math is on the frontrunner's side. One Romney adviser said last week that only an "act of God" could allow Santorum or Gingrich to win the nomination - tempting fate, perhaps.

But it's math, not divinity, that's  shaping the race. It leaves Santorum complaining that the race to the presidency shouldn't be about mere numbers.

"This isn't a mathematical formula," Santorum said on one Sunday morning show today.

"It's pathetic isn't it? I mean, now you're going to make the argument, 'I should be president,' because of math," he said on another.

Romney's is not an inspiring run for the White House at the moment.

But it doesn't have to be. Romney may win ugly, and it may take longer than he had hoped. Yet even for all the hits he's taking, Romney remains overwhelmingly likely to win the GOP nomination - winning by playing by the party's own rules.