Mitt Romney could all but guarantee he’ll be the GOP presidential nominee by winning Ohio on Super Tuesday.

A win there will hand Romney a chunk of delegates as well as a shot of momentum, making it hard for his opponents to catch him and bolstering the former Massachusetts governor’s argument that he’s the best choice to beat President Obama in the fall.

Ohio is a state that [Rick] Santorum cannot afford to lose,” said GOP strategist Alex Castellanos, who worked for Romney in 2008 but is neutral in this race. “If Santorum loses Ohio, it’ll be practically impossible to stop Romney.”