GRAND JUNCTION, Colo. (Reuters) — Republican presidential frontrunner Mitt Romney on Monday focused his campaign’s firepower on Rick Santorum to head off the former senator’s surge in two of three states with nominating contests this week.

Coming off a runaway victory in Nevada on Saturday, Romney hopes to cement his front-runner status on Tuesday in caucuses and primaries in Colorado, Minnesota and Missouri — the next battlegrounds in the state-by-state fight to pick a Republican challenger to face President Barack Obama in November.

Pollsters said Santorum, who has been vying with former House Speaker Newt Gingrich to be the conservative alternative to the more moderate Romney, was leading in Minnesota and was second to Romney in Colorado.

Santorum also has a good chance in Missouri, where Gingrich is not even on the ballot, although the vote there is just symbolic because there are no delegates up for grabs in the non-binding vote. Missouri delegates will be won in mid-March in the binding portion of a two-step process.