Last night demonstrated an annoying fact about the Republican-primary process: It’s complicated. Although Rick Santorum won two caucus votes and one statewide primary, he didn’t gain a single committed delegate to the national convention.

Two months ago, I imagined a scenario in which no candidate won enough delegates to clinch the nomination before the convention. Although I still think such an outcome is highly unlikely, it’s a fun thought experiment to rerun after these first few contests. I had pictured Santorum dropping out after Iowa (yeah, I know), and Mitt Romney and Newt Gingrich duking it out, while Ron Paul stole delegates here and there.

Now, the fight may be between Romney and Santorum, with Gingrich and Paul both swiping enough delegates to prevent either of the first two from claiming victory.

Here’s one more quirk that could cause problems: Much has been made about the winner-take-all states that are expected to put Romney over the top. But according to the Republican National Committee’s guide to state-primary rules, late states such as New York (95 delegates), Ohio (66 delegates), and Oklahoma (43 delegates) are winner-take-all only if one candidate receives over 50 percent of the statewide (or, in some cases, the congressional-district-wide) vote. In other words, if Santorum or Gingrich can keep Romney from topping 50 percent, they can steal some delegates for themselves.