CANTON, Ohio — Mitt Romney's allies are hoping Super Tuesday's powerful imprint on the Republican presidential nomination will bring clarity, at long last, to the fractious contest and rouse Republicans behind their frontrunner. But that's strictly up to voters across the nation, weighing in on most consequential day of the campaign to date.

AP Photo/Gerald Herbert

Republican presidential candidate, former Massachusetts Gov. Mitt Romney and his wife, Ann, left, greet patrons at the Montgomery Inn in Cincinnati, Ohio, Saturday.

Romney and his chief rival, Rick Santorum, scrambl...