Surging into top-tier contention, Republican Rick Santorum came under sharp criticism from rivals hoping to slow his momentum two days before Iowa's kickoff caucuses. The former Pennsylvania senator defended his record in Washington and cast himself as the most electable conservative alternative to front-runner Mitt Romney.
Polls showed Romney poised for a possible victory Tuesday in Iowa and Texas Rep. Ron Paul not far behind. Texas Gov. Rick Perry and Minnesota Rep. Michele Bachmann tried to make their case Sunday to peel conservative votes away from Santorum, whose meticulous campaigning across Iowa and wooing of social conservatives appeared to be paying dividends at the finish line.
"He's got a spending problem, he's got an earmark problem, he voted eight times to raise the debt ceiling in the United States Senate," Perry said on "Fox News Sunday."
Bachmann noted on the same broadcast that Santorum was soundly defeated when he ran for re-election in 2006, losing by a 59-41 margin to Democrat Bob Casey.
Santorum's campaign debuted a TV ad in Iowa that portrayed him as "a trusted conservative who gives us the best chance to take back America."
Joining rivals on the Sunday talk shows, Santorum was pressed to say whether he believed Romney had conservative values. Santorum said any of the Republican candidates would be more conservative than President Barack Obama.
"The question is, are those values ones that you can trust when they become president of the United States?" he told NBC's "Meet the Press."
Santorum defended his support for home-state spending projects, or earmarks, saying he was elected in part to bring federal money to Pennsylvania.
"I don't regret going out at the time and making sure the people of Pennsylvania - who I was elected to represent - got resources," Santorum said. But, he added, "I voted for some things that I look back and say, `Why the heck did I do that?'"
Santorum planned several campaign stops in western Iowa later Sunday.
Romney, who attended services at a Mormon church in West Des Moines, was set to appear in Atlantic and Council Bluffs as he works to maximize the edge he holds in critical areas rather than risk underperforming in places where more ardent conservatives are leery of his faith and shifting positions on social issues.
A new Des Moines Register poll found Romney with 24 percent support among likely voters in Iowa while Paul had 22 percent. Santorum place third with 15 percent, followed by Newt Gingrich, with 12 percent, and Perry, with 11 percent. Bachmann had just 7 percent support.
The poll's margin of sampling error for the full four days was plus or minus 4 percentage points. For the last two days, it was plus or minus 5.6 percentage points.
The poll showed Santorum gaining ground and Paul slipping a bit as rivals hammered him on his noninterventionist foreign policy views.
Paul, who spent the weekend at his home in Texas, stood firm on his contention that the U.S. should not bomb Iran if the country is developing a nuclear weapon.
"I would say that we just need to be more cautious. I think if we overreact and participate in bombing Iran we're looking for a lot more trouble," Paul told CNN's "State of the Union."
Santorum said that if he were president, he would bomb Iran's nuclear facilities unless they were opened for international arms inspectors.
Gingrich, battered by negative TV ads from rivals and a pro-Romney super political action committee, was fighting to stay in contention after topping the field in Iowa just weeks ago.
"Romney would buy the election if he could," the former House speaker told reporters after attending Mass in Des Moines with his wife, Callista.
Gingrich said he was encouraged by one finding in the new poll - that 41 percent of voters could change their mind about who to support.
Indeed, with many factors at play, the dynamics can shift rapidly.
Yet two things were clear on the final weekend before the caucuses: The yearlong effort to establish a consensus challenger to Romney had so far come up short, and Romney's carefully laid plan to survive Iowa may succeed because conservative voters had yet to unite behind one candidate.
Bachmann redoubled her effort woo evangelicals Sunday.
She took to the pulpit at Jubilee Family Church in Oskaloosa, where for more than 30 minute she guided the congregation to several favorite Bible passages and shared her testimony for giving herself over to God as a teenager in Minnesota.
"The Holy Spirit cleansed me and gave me a peace I'd never before had in my heart," she said
Perry had no campaign events planned after attending church in West Des Moines. He was to travel to Greenville, S.C., the day after the caucuses, bypassing next-up New Hampshire, which holds its primary Jan. 10. He intended to participate in two debates in New Hampshire next weekend.
Campaigning alone in New Hampshire, former Utah Gov. Jon Huntsman said it would be that state that sends a message about which candidate is most electable. He is skipping the Iowa contest and has made modest inroads in New Hampshire after months near the bottom of the polls.
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