Republican presidential candidates Mitt Romney and Rick Santorum are making last-minute appeals to Ohioans in a Rust Belt state where polls show a neck-and-neck race just one day before the Super Tuesday primary.

Ten states across all regions of the country will hold GOP nominating contests Tuesday.

Romney has a significant advantage in northeastern states like Vermont and Massachusetts and Santorum sees advantages in conservative states like Oklahoma. Ohio is a critical battleground that also has a history as a key general election swing state.

Santorum tells The Associated Press that Romney's inability to wrap up the nomination raises questions about whether he can beat President Barack Obama in November. He suggests that the GOP nomination may not be settled until this summer's party convention.