Romney works to fend off Santorum challenge

GRAND JUNCTION, Colo. -- With Rick Santorum posing an unexpected challenge in the next states to vote, Mitt Romney criticized his time in the Senate as "not effective" because of his past support for spending on pork-barrel projects.

Santorum countered that Romney, the front-runner in the GOP presidential race, "should not be our nominee" because he was "dead wrong on the most important issue of the day" when, as governor, he signed a health care overhaul into law in Massachusetts.

The two sparred from afar Monday, one day before Republicans in Colorado and Minnesota hold nominating caucuses.

Former House speaker Newt Gingrich and Rep. Ron Paul of Texas also are competing but neither was expected to have a breakout performance in either state.

Romney, who won both states four years ago, hopes to extend his winning streak, though advisers acknowledged that a first-place finish would be more likely to come by in Colorado than in Minnesota.

The Republican Party in Minnesota has become more conservative in recent years and Santorum's strong conservative positions on social issues could resonate with the state's strong contingent of evangelical voters.

Some polls show Santorum was leading in Minnesota and was second to Romney in Colorado.

Santorum, a Catholic from Pennsylvania, has a strong anti-abortion record and consistently focuses on the issue. Romney, who once supported abortion rights, has struggled to win over those voters. But in a sign that he's trying to do just that, Romney's campaign Monday rolled out a petition focusing on religious liberty.

The move was intended to challenge a recent Obama administration decision to require hospitals to distribute free birth control, a policy at odds with the religious teachings followed at many Catholic health care facilities.

Clearly mindful of the shift in Minnesota, Santorum has been working that state and conservative areas of Colorado aggressively in the past two weeks while Romney campaigned in Florida and Nevada and scored back-to-back victories. It was clear Monday that Santorum saw an opportunity to rise in the GOP race.

In an appearance across the street from the highly regarded Mayo Clinic in Rochester, Minn., Santorum assailed Romney with gusto and said that making him the nominee would be "a devastating thing" for Republicans who want to see President Barack Obama lose in the fall.