After Rick Santorum won the Colorado, Minnesota, and Missouri contests on February 7, his supporters were disappointed to learn he hadn’t gained any pledged delegates to the Republican national convention. In fact, it is highly likely none of Colorado’s 36 delegates will be bound to a candidate. Just three days before, however, Mitt Romney had won the Nevada caucuses — and 14 pledged delegates with them.

What gives? The rules regarding delegates’ voting responsibilities vary state by state. “There are 50 states,” notes Bill Crocker, Republican national committeeman for Texas. “And so there are probably 53 answers” to this question, he jokes.

In short: Bound delegates must vote for a certain candidate, while unbound delegates are free to vote their preference. Complicating this picture, however, are rules on the length of the delegates’ stipulated commitment and the lack of enforcement mechanisms.

Each state receives three types of delegates: automatic delegates (the state-party chairman, state committeeman, and state committeewoman), congressional-district delegates, and at-large delegates. In some states, such as Iowa, state law and party rules are silent on their distribution. The state’s delegates are elected at a convention in June, and they’re free to vote for whichever candidate they prefer. But in other states, such as New Hampshire, state law requires that the party allocate its delegates proportionally according to the statewide vote.

And in some states, state-party rules reign. In Texas, for instance, GOP rules require the 155 delegates to vote proportionally according to the state-primary vote. “The delegates are bound for three ballots and can only be released [before then] by the candidate withdrawing,” Crocker says. “Then for our purposes down here, the votes for that candidate will be reapportioned among the remaining candidates according to their proportion of the primary-ballot vote.”

Delaware, meanwhile, is a winner-take-all contest, and all delegates are bound to the victor — though for only the first ballot. And unlike in some states, in which the candidates themselves select their delegates, in Delaware, the delegates run on their own. Of Delaware’s 17 delegates, five of them are elected as representatives of the state’s five political districts by the state-committee members within those districts. Nine others are chosen by state-party officers.

Wisconsin is a whole other ballgame. In the Badger State, the 15 at-large delegates will go to whoever wins the statewide primary, but the 24 congressional-district delegates will go to whoever wins their respective districts. In other words, it’s possible for a candidate to win all the at-large delegates, but lose some of the congressional-district delegates.

And in West Virginia, it’s even more complicated. Voters elect 28 delegates directly, and each voter makes 22 choices (19 for the at-large candidates and three for the congressional-district candidates). On May 8, the primary day, a voter will go into the voting booth, and on the primary ballot he’ll see each of the candidates’ names with a list of delegates pledged to that candidate underneath. That voter then will be able to distribute his votes any way he likes: say, ten for Santorum, four for Mitt Romney, four for Newt Gingrich, and one for Ron Paul.

Unfortunately for Santorum, because the state’s filing deadline passed in January, he won’t have the maximum amount of delegates who could run in his name. “In one of the congressional districts, he doesn’t have anybody,” reports Donna Gosney, Republican national committeewoman for West Virginia (who is supporting Romney). And in another twist, Republicans can even vote for uncommitted delegates in West Virginia.