WASHINGTON - GOP presidential rivals made contrasting appeals to conservatives Friday, with Mitt Romney saying he proved his mettle as Massachusetts governor and Rick Santorum saying Romney is so moderate that electing him would be a "hollow victory."

Their speeches to the Conservative Political Action Conference came as Santorum tries to convert his surprising caucus wins this week into a resilient, muscular campaign and Romney seeks to persuade conservatives that he won't disappoint them.

Santorum's tack was unorthodox, and perhaps risky. Facing Republicans who desperately want to replace President Barack Obama, Santorum said it's even more vital to put a conservative crusader into the White House.

"We will no longer abandon and apologize for the policies and principles that made this country great for a hollow victory in November," he said.

If voters see that as a hint that it's more important to be ideologically pure than to oust Obama, Santorum may have to explain more fully in the days ahead.

Romney, speaking a few hours later, said his four-year record in Massachusetts proved that he will fight for conservative values against the toughest odds. "I know conservatism because I have lived conservatism," he said. Veering briefly from his written text, he called himself "severely conservative."

But Romney skated past details of his administration that trouble some right-leaning groups, including requiring state residents to obtain health insurance.

Without saying Romney's name, Santorum said the former governor's health care record would make it impossible for him to draw needed contrasts with Obama. He said Romney had created "the stepchild of Obamacare."

Saying the Obama-backed 2010 health care law "will crush economic freedom," Santorum urged Republicans not to nominate "someone who would simply give that issue away in the fall."

Santorum warned Republicans against a premature emphasis on moderate voters, who could decide the presidential election in swing states.

"We always talk about, 'Oh, how are we going to get the moderates?"' Santorum said. "Why would an undecided voter vote for a candidate of a party who the party is not excited about?"

Romney alluded to his rivals obliquely, never saying their names. Presidential leadership "isn't about getting a bill out of subcommittee or giving a speech," he said. "I am the only candidate in this race, Republican or Democrat, who has never worked a day in Washington."

His remarks appeared aimed at former Pennsylvania Sen. Santorum, former House speaker Newt Gingrich and Rep. Ron Paul, all of whom spent years in Congress. Gingrich was scheduled to address CPAC later Friday. Paul was not scheduled to address the conference.

Romney tried to reassure the audience that antipathy to Obama will energize millions of voters this fall, an indirect way of saying the lukewarm reception he gets from some conservatives isn't crucial.

Obama "is the conservative movement's top recruiter," he said.

Romney said he would cut federal spending like he cut state spending in Massachusetts, although he vowed not to touch military budgets.

"I was a conservative governor," he said. "I fought against long odds in a deep blue state. I understand the battles that we, as conservatives, must fight because I have been on the front lines."

Santorum and Romney criticized the Obama administration's bid to require Catholic-affiliated employers to cover birth control in their health insurance plans. After Santorum's morning speech and before Romney's afternoon address, Obama announced an update. He said religious-affiliated employers will not have to cover birth control for their employees. Instead, the government will demand that insurance companies be directly responsible for providing contraception.

Santorum, a Catholic with a strong record of fighting legalized abortion, said Obama is "telling the Catholic Church that they are forced to pay for things that are against their basic tenets and teachings."

"It's not about contraception, it's about economic liberty," he said.

Romney, a Mormon who once supported legalized abortion, vowed to reverse "every single Obama regulation that attacks our religious liberty and threatens innocent life."

His critics cite a 2005 interview in which Romney said rape victims deserved either access to or information about so-called morning after pills that some say are a form of abortion.

Both men restated their standard criticisms of Obama. Romney called him "the poster child for the arrogance of government."