Mitt Romney is hoping to become unstoppable after a presumed victory in Florida Tuesday night, but don’t count out his opponents, particularly the dark horse in the race, Rick Santorum, who’s polling a far-back third nationally but has seen his support rise with Newt Gingrich’s recent struggles.

Santorum, who decided to forego Florida, is spending his time in other states, returning to the trail Monday for a schedule that included Missouri, Minnesota and Colorado, and saying he’s not bailing on a race where delegates are divvied up, rather than winner-take-all.

If Santorum outperforms in the polls in Florida, it would help him make the case that he’s a better challenger than Gingrich against President Obama. But even without the vote, Santorum said he’s not only the true conservative, but the one who knows how to win in a swing state.