Santorum has a big delegate problem in Ohio

Altogether, this means Santorum, who until this week had a fair lead in polls in the Republican nominating race, could be ineligible for 18 Ohio district delegates.

Ohio has 66 delegates total, 63 at stake next Tuesday. The candidate with the most delegates wins. Santorum therefore goes into the Ohio primary election with a 29 percent deficit.

What will happen if he wins in a district where he failed to allocate a full slate of three delegates?

In the short term, he will be eligible to take only the delegates he has already allocated in that district, the party says. Yet he will have won that district — so the unallocated delegates will not be awarded to anyone else, either.