Mitt Romney squeezed out a win in pivotal Ohio, captured four other states with ease and padded his delegate lead in the race for the Republican presidential nomination but was forced to share the Super Tuesday spotlight with a resurgent Rick Santorum.

On the busiest night of the campaign, Romney scored a home-state win in Massachusetts to go with primary victories in Vermont and in Virginia _ where neither Santorum nor Newt Gingrich was on the ballot. He added the Idaho caucuses to his column.

Ohio was the big win, though, and the closest contest of all.

Santorum countered crisply, winning primaries in Oklahoma and Tennessee and the North Dakota caucuses _ raising fresh doubts about Romney's ability to corral the votes of conservatives in some of the most Republican states in the country.