Romney sensed a challenge and pivoted somewhat from his predominantly economic message to focus on high-profile cultural issues this week as he worked to reassure voters that he stood with them.
He stood by the decision —later reversed — by the Susan G. Komen for the Cure breast-cancer charity to stop contributing to Planned Parenthood. He also criticized the Obama administration for its decision to require church-affiliated employers to cover birth control, calling that an "assault on religion" and "a real blow ... to our friends in the Catholic faith."
His assurances didn't work.
The new furor over abortion rights reminded some voters of Romney's shaky past on the issues.
"Governor Romney has been very good about saying he's the most electable. But he just hasn't been able to resonate with caucusgoers, who are the more conservative part of the party. How do we know he's really a conservative because he hasn't governed as a conservative?" said Gary Borgendale, a Santorum supporter and Christian radio director from Minneapolis. "Some of the issues that have come out in the last two weeks are waking people up. There is a choice."
Exit and entrance polls conducted for The Associated Press in the first five GOP contests showed that voters who are looking for a "true conservative" have not been backing Romney. In Florida and New Hampshire, where he won by large margins, he earned support from just over 10 percent of these voters.
Romney's performed more strongly among moderate and liberal voters in Iowa, New Hampshire, South Carolina, Florida and Nevada. He has won over voters who describe themselves as conservative a few times, but not by dominating margins outside of New Hampshire, where he was expected to win, and Nevada, where about a quarter of voters share his Mormon faith. He was the preferred candidate by very conservative voters only in those two states.
This year, Romney has strategically avoided putting himself at the mercy of more conservative voters who dominate caucuses. The approach was born after he was stung after waging a $10-million campaign for Iowa's 2008 caucuses, only to lose to underdog Mike Huckabee.
Romney's calculation this time cost him votes in GOP strongholds such as Colorado's El Paso County, which he dominated four years ago.
Some activists who attended the county caucus in Colorado Springs voiced strong objections to Romney, although more noted Santorum's aggressive campaign while the 2008 winner was largely absent. Romney won the county with nearly 60 percent of the vote in 2008, but managed only 30 percent Tuesday night. Santorum won the county with 47 percent of the vote, having visited four times in the final week of the campaign.
"It was about grass-roots campaigning," El Paso County GOP Chairman Eli Bremer said. "Many, many more people had met Rick Santorum than had met Mitt Romney. Some conservatives at the caucus voiced concern about Romney. But more people were voting for Santorum rather than against Romney."
Thomas Beaumont reported from Des Moines, Iowa. Associated Press deputy director of polling Jennifer Agiesta contributed from Washington.
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