ATLANTA — Mitt Romney still can't seem to win over the bulk of the conservatives who make up the bedrock of the Republican Party.
Despite primary victories that have established him as the GOP presidential front-runner, his stunning trio of defeats this week laid bare the difficulties that still could undercut his path to the party's nomination — and hamper him in the general election to follow.
Not that he would acknowledge as much Wednesday.
"I don't think the conservative base changes its mind day to day," Romney told reporters, dismissing the notion that he's got a problem with the party's core supporters. "The places where I campaigned actively, we got actually in some respects record support from the conservative base."
Such denials aside, Tuesday's three-state caucus sweep by Rick Santorum illustrated the degree to which many conservative voters remain skeptical of Romney's commitment to the GOP base's principles, especially given what some of them see as his history of shifting priorities. And he hasn't been able to sell them on his main argument — that he's the most likely in the primary field to beat Democratic President Barack Obama.
"The more confidence the strong conservatives have in the alternative candidates, the more Romney's lack of strength in those categories starts to show itself," said Iowa Rep. Steve King, a conservative who has been publically neutral in the nomination race.
To rebound, Romney is working to make his chief rivals — all of them running to the right of him — unacceptable in the eyes of conservatives by casting them as big-spending Washington insiders.
"A lot of us feel that the Republican Party lost its way in the past," Romney said Wednesday. "Republicans spent too much money, borrowed too much money, earmarked too much, and Rick Santorum and Newt Gingrich have to be held accountable."
Romney, who has struggled to win tea party support, also is appealing directly to the movement saying that it formed because Americans were unhappy with incumbents.
"In this race, I'm the only guy that hasn't spent time in Washington," Romney said. "And Senator Santorum and Speaker Gingrich, they are the very Republicans who acted like Democrats. And when Republicans act like Democrats, they lose. And in Newt Gingrich's case he had to resign. In Rick Santorum's case, he lost by the largest margin of any Senate incumbent since 1980."
The former Massachusetts governor who governed as a moderate chalks up his weak showing Tuesday among the GOP's most devout activists in Colorado, Minnesota and Missouri to his campaign's focus on running a national campaign. He's pointing instead to his huge comeback win in the Florida primary last month and follow-up in the Nevada caucuses last weekend.
"We didn't devote a lot of money and time to the states yesterday. We were spending our time and money in Florida and Nevada," Romney said. "And Senator Santorum took a different course, left Florida, left Nevada, went to the other states and he was able to reap the rewards of that approach."
Romney's strongest performances have been in states where he has spent heavily on advertising and has benefited from attacks on his rivals by a political action committee run by his allies. Those victories — coupled with a New Hampshire win —have given him the lead in the race to amass the most delegates to the party's nominating convention, and he also leads his rivals in the money chase.
The front-runner has two weeks to address the conservative angst surrounding his candidacy before facing the next critical test of his standing among conservatives. It comes on Feb. 28 in the Arizona primary, where tea party and conservative activists have shown strength in recent elections, and the Michigan primary, a must-win for Romney where Santorum has pledged to compete aggressively.
Santorum's wins in Colorado and Minnesota — where Romney won during his 2008 campaign for the nomination — and Missouri were a testament of sorts to the power of low-dollar, personal campaigning. The former Pennsylvania senator bypassed Florida to visit the trio of states repeatedly. The contests were low-turnout affairs with electorates that were close matches with his deep social conservative profile.
With that in mind, Santorum emphasized his conservative credentials, contrasting them with Romney's changed positions on some social issues.
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.