Frontrunner Mitt Romney hoped to keep momentum on his side and deliver a major blow to chief rival Rick Santorum as the two candidates waged a closely fought battle over Ohio, seen as the biggest prize of the day. Harry Young, a 60-year-old engineer, voted moments after polls opened at 6:30 am (1130 GMT) in Dublin, Ohio, outside the capital Columbus. He told AFP he pulled the lever for Rick Santorum, a Christian conservative, "basically because of values." But he wasn't entirely confident that either Santorum or Romney would be able to carry the day against President Barack Obama, a Democrat, in November's general election. "I'm not sure either of them can do it at this point, they've been beating each other up so much," he said. Hank McCormick, 65, a precinct manager for the polling station, said he voted for Romney.