ABC News' Michael Falcone reports:
UPDATED: COLUMBUS, Ohio - Even if Rick Santorum wins Ohio on Super Tuesday, he won't be able to claim all of its delegates. In fact, he is at risk of forfeiting more than one-quarter of them.
In three of the state's 16 congressional districts, including two that are near Ohio's border with Pennsylvania, Santorum will lose any delegates he might have won because his campaign failed to meet the state's eligibility requirements months ago.
Those three districts alone take 9 delegates out of a total of 66 off the table for Santorum.
But it gets worse: Nine more Ohio delegates may also be in jeopardy.
Sources say that in six other congressional districts - the third, fourth, eighth, tenth, twelfth and sixteenth - Santorum submitted fewer names than required to be eligible for all three delegates up-for-grabs in each district.
That means even if he wins in those places, he might not be able to receive the full contingent of delegates.
In the three districts where Santorum did not submit a delegate slate at all, he will not be able to receive any delegates. In the six where he submitted only a partial slate, he is eligible to be awarded only the number of delegates he submitted, assuming he wins a particular district.
Chris Maloney, a spokesman for the Ohio Republican Party, said the leftover delegates will be considered "unbound" and the campaigns will be able to file a petition with the state party to claim them. Once such a petition is filed, Ohio GOP Chairman Kevin DeWine is required to impanel a "committee on contests" composed of three members of the Ohio GOP's central committee to sort out the delegate awards.
What's clear is that Santorum will be competing in Ohio on Tuesday handicapped by the fact that he is ineligible to receive nine delegates and perhaps as many as nine more, or more than one-quarter of the state's delegates.
Worse yet, some of these problem districts are in areas of the state where Santorum is expected to do well. The sixth congressional district, for example, hugs Ohio's eastern border with West Virginia and Pennsylvania - the state Santorum represented in Congress. The thirteenth district, which includes Akron, is nearby.
Notably, Santorum plans to spend election night in old steel town of Steubenville, Ohio, located in the sixth district, even though he has no chance of collecting any of the district's three delegates.
The bar to file what's known in election parlance as a "full slate of delegates" in each district was not particularly high. Candidates were required to submit the names of three delegates and three alternates per district.
According to the Ohio GOP, the Santorum campaign is missing the names of one delegate in the state's third district, two in the fourth, one delegate in the eighth, two delegates in the tenth, one delegate in the twelfth and two delegates in the sixteenth. Santorum's opponents - Mitt Romney, Ron Paul and Newt Gingrich - each filed full slates in all of Ohio's districts as did two candidates who are no longer in the race, Rick Perry and Jon Huntsman.
In other words, Santorum needed to submit 48 names in order to be eligible to compete for all of state's district delegates outright.
Santorum is facing a high-stakes contest with Romney in Ohio. A Quinnipiac University poll released on Friday showed the former Pennsylvania senator with a slim four percentage point lead over Romney in the state, 35 percent to 31 percent. Roughly one-third of likely Republican primary voters said they could still change their mind before Tuesday.
And as the Republican nominating contest becomes as much a battle for delegates as it is for momentum, Santorum's difficulties in Ohio offer another window into the organizational challenges his campaign has faced throughout the primary season. Santorum is not on the ballot in Virginia, which also holds a primary on Super Tuesday and where each candidate was required to submit 10,000 signatures, including 400 from each of the state's 11 congressional districts.
The eligibility requirements in Ohio were comparatively easier, but at the time Santorum's rivals were putting together their delegate slates in December, Santorum was crisscrossing Iowa in a pickup truck ahead of the caucuses, which he ended up winning by a hair. The deadline for submitting the slates in Ohio was the last week of December.
There are a total of 63 delegates up for grabs in Ohio on Tuesday, 48 of them are awarded proportionally based on who wins the popular vote in each Congressional district - three per district - and 15 will be awarded to the candidate who wins a majority of votes in the state. However, if no candidate surpasses 50 percent of the vote, the "at-large" delegates are awarded proportionally to each candidate who received more than 20 percent of the statewide vote. Three additional party leaders will act as unbound delegates at the Republican National Convention, but they will not be awarded on Tuesday.
The Romney and Santorum campaigns offered vastly different takes on the delegate situation in Ohio.
"The attempt by the establishment to to deceive the voters of Ohio and further their hand-picked candidate will be met with resistance on Tuesday. I want to be clear, Rick Santorum's name will appear on every ballot in the state of Ohio and every vote cast will go towards his At-Large Delegate Allocation," Santorum campaign communications director Hogan Gidley told ABC News. "As it relates to individual Congressional Districts, it's clear we aren't the establishment hand-picked candidate and back in December we were a small effort focused on Iowa. Now that we've won several states Obviously much has changed and we feel confident that we will do well in both the delegate and popular vote count on Tuesday."
Romney campaign spokesman Ryan Williams said that the Santorum campaign's shortcomings in the state was a sign of weakness.
"Rick Santorum has failed to get on the ballot in Virginia, has failed to file full delegate slates in Tennessee, New Hampshire and Illinois, and has failed to submit enough delegates in several Ohio congressional districts," Williams said in a statement. "The fact that he cannot execute the simple tasks that are required to win the Republican nomination proves that Rick Santorum is incapable of taking on President Obama's formidable political machine."