The race for the Republican presidential nomination is about to take a big step forward, with 10 states weighing in Tuesday on the biggest day of voting yet in the two-month-old campaign.

With several key contests set for so-called "Super Tuesday" -- from the swing state of Ohio to the delegate-rich Georgia -- the four remaining candidates have pursued varying strategies for capitalizing on the day's voting and gaining momentum.

Mitt Romney remains the front-runner and could use a dominant showing Tuesday to all but eliminate doubt about his inevitability. But Rick Santorum continues to present a strong challenge, and polls have remained close in Ohio, a Midwestern industrial state where voters have an uncanny history of picking winners in presidential politics.

Newt Gingrich, the former speaker of the House of Representatives, is banking the future of his candidacy on winning in his home state of Georgia, where he holds the lead in polls.