DENVER — Mitt Romney just can't shake his difficulty attracting conservatives. And that reality is undercutting his effort to cast himself as the inevitable Republican presidential nominee, prolonging a race that each day exposes deep divisions within the party.
Newt Gingrich also now faces a fresh challenge to his claim that he's the chief conservative alternative to Romney.
Those were the big takeaways from Rick Santorum's surprise victories Tuesday night in Colorado, Minnesota and Missouri — which, for now at least, keep his struggling candidacy alive.
The former Pennsylvania senator told cheering supporters Tuesday he was not "the conservative alternative to Mitt Romney," but rather "the conservative alternative to Barack Obama."
Santorum broke a four-state losing streak by successfully pitching himself as the only true conservative in Tuesday's races.
The results focus attention on Romney's and Gingrich's weaknesses, while underscoring the degree to which the GOP primary battle is likely to stretch well into the spring and perhaps even the summer. The outcomes also are likely to detract from Republicans' efforts to lambaste President Barack Obama.
Despite the momentum boost for Santorum, it's unclear whether the cash-strapped candidate has the resources to capitalize quickly on the wins and compete against Romney's national political machine.
Santorum is a candidate with a post office box as a national headquarters. He's using volunteers to handle his scheduling. And he has virtually no staff to help turn momentum into votes in the critical Super Tuesday contests four weeks away.
However, his rivals face problems of their own.
Romney has struggled to win over conservatives, who for years have viewed him skeptically for his shifts and reversals on issues they hold dear, like abortion and gay rights. He hadn't lost a nomination fight since his second-place finish in South Carolina 18 days ago and had since won the Florida primary and Nevada's caucuses. Polling in those two states even suggested that Republicans of all stripes — social conservatives, tea-party activists and those in the mainstream — had finally begun to set aside doubts about his conservative credentials.
As a result, Romney had started to portray himself as the presumptive nominee as establishment Republicans rallied behind him.
But in recent days, Romney sensed a Santorum surge in Colorado, Minnesota and Missouri, and started to court social conservatives with get-tough positions against abortion and gay rights as he worked to convince them that he was pure on key issues despite his more moderate positions of the past.
Gingrich, for his part, did his best to ignore one of his worst days in the campaign in which he finished far behind Santorum and Romney. The former House speaker spent Tuesday campaigning in Ohio and staying out of sight when results rolled in from Minnesota, Colorado and Missouri. And he had no immediate comment on an outcome that put into question his standing in the race.
Gingrich is trying to project strength heading into a series of Super Tuesday elections on March 6, but his decision to barely campaign in the trio of states this week gave Santorum the opportunity to suggest that he's the real anti-Romney candidate.
The race now moves to Maine, whose low-profile caucuses conclude Saturday, before heading to Arizona and Michigan. Romney is poised to do well in Michigan, given his family ties to the state his father once governed.
History may reveal Tuesday's results were little more than an embarrassing blip for a Romney campaign that holds massive advantages over underfunded and under-organized rivals. But it may take months to find out.
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Steve Peoples covers national politics and the presidential campaign for The Associated Press.


