Transcript for Super Tuesday: Can Romney Win Ohio?
This is this the super -- night which usually changes everything voters in ten states are lining up at the polls. Right now as we are on the air from North Dakota to Georgia. Idaho at a Massachusetts. So is this might Mitt Romney virtually locks up the race and what will Rick Santorum do. Our team is on the ground as your voice your vote is rolling and an ABC's David -- Jon Karl spent the day with the candidates as they -- -- finish line. Let's Begin right now with David York David. Diane no question this is a critical evening for Mitt Romney were at his headquarters here in Boston. If he does well this Super Tuesday and particularly this evening in Ohio. This could be the night when he seals the deal on this nomination making it nearly mathematically impossible. For the other candidates to catch up. Late today Mitt Romney's wife and coming back to their home Massachusetts to vote in Belmont our cameras trained on their every move there and -- We caught a moment where he was -- holding his ballot he smiles at his wife. To keep in mind this is a guy has been running for president for six years now most recently declaring last June of course in neighboring New Hampshire. We saw that waved to the crowd and then everything that followed the holding of the babies the parades the debates the state fairs. Elizabeth the crunch the numbers tonight 21 states. Ten campaign -- that we its 360 events in the debates themselves Diane 32 hours 31 minutes of debate. The governor just moments ago saying too hard to predict what will happen tonight but we can predict what -- -- effort dinner. His son tag making him dinner and and dinner is -- to bring over some chicken Marcelo we're told. Asparagus and some mashed potatoes. They want Ohio for dessert no question but I got a question for you Diane and Jon Karl over Rick Santorum here's what's on the menu there in Ohio. All right John what about that. Well no big dinner plans the Santorum to gonna have a little's a spaghetti but they'll be watching these returns anxiously. Rick Santorum sees this as his -- Vs Goliath moment up against an opponent that has vastly outspent him out organize them. An opponent who has has the endorsements of all Republican Party. Things going into today's big primaries Santorum was sounding positively in this -- about all he has been able to achieve so far. That. The people of America saw a guy from. Little steel town of southwestern Pennsylvania. Go out and take his message on the road in Iowa. Driving around -- the chuck truck a Dodge Ram pick up with about 200 some thousand miles on it. Santorum told me that no matter what happens today is already winning. Just to be in this race at the level that he is but make no mistake Diane diet yet Santorum needs to score big here today if he's got any chance of capturing -- road. Republics and John talented -- standing by all evening as the results -- and I want to bring -- George Stephanopoulos right now so -- Mitt Romney in the nominate. Almost certainly I think what could look what we know right now Mitt Romney -- win the most states tonight. He will certainly win the most delegates in at the end of the night -- will be the only candidate in the field. Who can actually win enough delegates to get this locked up before the conventions he can secure his claim to the nomination only. He does beat Rick Santorum in that big battleground state of Ohio. That's what it means watching -- and you and -- -- -- over the exit polling and so there's a vulnerability. In here we can really see Mitt Romney's challenge if he does get this nomination tonight in Ohio voters go to the polls regardless of other gonna vote. They believe the Mitt Romney is the most electable 53%. Think he's got the best ability to be President Obama but. When you ask who understands the problems of average Americans look at that. Only 23%. Say Mitt Romney he's got a real connection problem here not -- similar. To a Barack Obama had four years ago ten because of problems of average Americans and that's right there -- -- of those -- George and I will be standing in the polls bringing you more of that. Tea leaves that they bring us tonight from the election tonight and modest com be sure to stay with us -- the ten states come -- -- this decisive. Voting night we hope you'll join us throughout the evening thank you George.
This transcript has been automatically generated and may not be 100% accurate.