WASHINGTON — Republicans in Colorado, Minnesota and Missouri will vote for presidential candidates Tuesday, and while Mitt Romney is favored to win, many conservatives appear eager to signal their unease with him by voting for Rick Santorum.
Social conservatives are particularly active in Minnesota, where one poll has Romney, a former Massachusetts governor, in a virtual tie with former Pennsylvania U.S. Sen. Santorum.
Polls are often poor predictors of caucus results, however, where attendance is a function of campaign organization and voter passion.
"Caucus attendees here tend to gravitate to the most conservative candidate," said former Minnesota Gov. Tim Pawlenty, a Romney supporter. Santorum has been emphasizing family and faith, painting himself as the race's true staunch conservative.
Santorum questioned Romney's conservative credentials Monday, while the Romney camp painted Santorum as aggressively spending federal money during his Senate years.
Public Policy Polling, a Democratic survey firm, found Santorum ahead of Romney by 29 to 27 percent in its Saturday poll, and called the race a toss-up. Not far behind were Newt Gingrich, a former speaker of the House of Representatives, with 22 percent and Texas U.S. Rep. Ron Paul, at 19 percent. Paul has campaigned hard in the state; Gingrich has made little effort.
"Maybe 60,000 people will turn out, in a state where millions of people vote" in general elections," said Steven Schier, a professor of political science at Carleton College in Northfield, Minn. "It's a sliver of a sliver. Santorum knows that, and he's been here and he's been active."
Colorado's caucuses are less of a risk for Romney, though tea party candidates won statewide primaries there last year before losing in the general election. Romney has a strong state organization and has campaigned hard there in recent days, while Gingrich and Santorum aren't as well organized there.
Missouri also will vote Tuesday, albeit in a nonbinding primary that will select no delegates to the Republican National Convention in August. They'll be selected later.
The caucus states will be watched most closely. A Romney stumble Tuesday is unlikely to derail his march to the nomination, though it would revive questions about his political strength. He won both state caucuses in 2008.
This time, "losing one of these races is not game changing," said Floyd Ciruli, a Denver-based independent political consultant. "But it would be a lifeline for one of the other candidates."
If social conservatives signal their displeasure with Romney, that could add drama to a GOP battle that's widely considered effectively over after Romney's big wins last week in Florida and Nevada.
"Santorum has great appeal to some of those people," said Charles Slocum, a former Minnesota GOP chairman. Many conservatives, Slocum said, think that Romney's record "has not been consistently conservative enough."
Among their beefs: Romney signed into law a state health care plan that became the model for the 2010 federal health care law. He's said the plan was right for Massachusetts but shouldn't be imposed nationally.
"The only area conservatives would appreciate Romney flip-flopping on would be Romneycare," Santorum spokesman Hogan Gidley said. "So why he doubles down on this liberal accomplishment instead of just flip-flopping as usual is beyond me."
The Romney camp aggressively confronted the Santorum threat Monday. It issued a "research briefing" on Santorum's "false attacks on Massachusetts health care."
Santorum said at a candidates' debate Jan. 26 that Romney backed a "top-down, government-run health care system." Massachusetts law requires nearly everyone to obtain insurance and provides assistance to those who can't afford it, but it doesn't create a government-run system.
Later Monday, Pawlenty conducted a media conference call on "Rick Santorum's Long History of Pork-Barrel Spending," listing different earmarks, or local projects, that Santorum backed while he was a U.S. senator from 1995 to 2007.
Santorum said that by helping his state, he was doing his job as a senator.
Colorado is safer Romney territory; Public Policy Polling has him up there by 14 points. "He's put in a lot of time here," Ciruli said. "The leadership is comfortable with him. They were with him four years ago, and he has all the same people back."
Adding to his popularity are his ties to neighboring Utah, where he rescued the 2002 Winter Olympics, and a sense that in a swing state such as Colorado, "he's the strongest general election candidate," Ciruli said.
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