"Ronald Reagan was a president of strength," Mitt Romney intoned. "Ronald Reagan used to say, we spend money like a drunken sailor," said John McCain (news, bio, voting record). And Rudy Giuliani praised "that Ronald Reagan optimism."

The world, however, is far different today than it was some 25 years ago when the nation's 40th president relaxed at his retreat in the rolling hills of southern California.

Iraq and terrorism now are top issues, support for Bush is at a low point and Republican hopefuls find themselves trying to prove to the party's base that they're conservative enough to be the GOP nominee — on social matters as well as the economic and security issues Reagan championed.

The three leading candidates — Giuliani, McCain and Romney — and their seven lesser-known rivals attempted to do just that Thursday at the Ronald Reagan Presidential Library. They debated for 90 minutes in the shadow of the late president's Air Force One suspended from above and before Reagan's widow, Nancy, who sat in the front row of the audience.

They stressed the importance of persisting in Iraq and defeating terrorists, called for lower taxes and a muscular defense, and supported spending restraint.

One by one, they invoked Reagan 19 times. In contrast, Bush's name was barely uttered; the president's job approval rating languishes in the 30s.

"They went out of the their way on multiple occasions, no matter the question, to associate themselves with Reagan," said Mitchell McKinney, a political communication professor at the University of Missouri-Columbia. "They tried their best to not be explicitly bashing or attacking Bush. Most of them tried, in some way, to take a pass on that."

Republican operatives agreed that the debate did nothing to shake up the crowded GOP field.

They said Giuliani, the former New York City mayor, McCain, a four-term Arizona senator, and Romney, the ex-Massachusetts governor, remained the strongest contenders, with the most money and the best approval ratings in the polls more than eight months before the first 2008 national convention delegates are selected.

"Clearly the top three looked quite presidential," said Whit Ayres, a Republican pollster.

Scott Reed, who ran Bob Dole's 1996 campaign, added: "McCain showed a little energy. Romney showed he's very polished. And Giuliani started to clear up some of his issues with the base of the party."

Each largely stuck to their talking points — and often reverted to their stump speeches — as they sought to present themselves as the most conservative candidate in the pack, and a worthy heir to the political legacy of Reagan.

The former actor and California governor took office in 1981 when the world was absorbed by the Cold War, and good versus evil was defined by countries that aligned with the United States and those that stood with the Soviet Union — "the evil empire" in Reagan's lexicon. The arms race and the ever-present threat of nuclear war overshadowed social issues like abortion. Stem cell research didn't exist. There was no public debate about gay marriage or the so-called right to die.

Fast forward to the 2008 presidential race.

The candidates expressed resolve in winning the war in Iraq and defeating terrorists across the world. They also had to answer for their positions on a range of social issues, including abortion, stem-cell research and evolution.

"Nobody wants to talk about social issues for more than 11 seconds," said Rich Galen, a GOP strategist. "But they had to talk about what they were asked about."

McCain is the only top-tier contender who has a career-long record of opposing abortion, a position that resonates with a wide swath of GOP political activists who support the overturning of the 1973

Roe v. Wade ruling that legalized abortion.

With a record of supporting abortion rights, Giuliani was the only candidate who said "it would be OK" if the Supreme Court upholds the landmark ruling. "It would be OK to repeal it. It would be OK also if a strict constructionist viewed it as precedent," he said.

His rivals agreed that it would be a great day if the court overturns the landmark ruling.

Romney, for his part, acknowledged he had reversed course on the subject and said his position had once effectively been "pro-choice."

"I changed my mind," Romney said, adding that Reagan did the same.

But Giuliani, who said he personally hates abortion, hedged when asked about his current position.

"I think the court has to make that decision and then the country can deal with it," he said. "We're a federalist system of government and states can make their own decisions."

Most of the contenders said they opposed legislation making federal funds available for a wider range of embryonic stem cell research. The technique necessarily involves the destruction of a human embryo, and is opposed by many anti-abortion conservatives as a result.

There are exceptions, though, including Reagan's widow, Nancy. Also, public opinion polls show overwhelming support for the research, which doctors say holds promise for treatment or even cures of numerous diseases.

McCain was the only one to unambiguously say he supports expanded federal research into embryonic stem cells.

Giuliani's response was open to interpretation. He said he supports it "as long as we're not creating life in order to destroy it," then added he would back funding for research along the lines of legislation pending in Congress. However, the bill he cited does not increase federal support for research on embryonic stem cells. Rather, it deals with adult stem cells.

The field split on another issue, with Sen. Sam Brownback (news, bio, voting record) of Kansas, former Arkansas Gov. Mike Huckabee and Colorado Rep. Tom Tancredo raising their hands when asked who did not believe in evolution.

Other participants included former Govs. Jim Gilmore of Virginia and Tommy Thompson of Wisconsin; and Reps. Duncan Hunter (news, bio, voting record) of California and Ron Paul (news, bio, voting record) of Texas.

Missing were three Republicans still weighing whether to run — Fred Thompson, the actor and former Tennessee senator; Newt Gingrich, the ex-House speaker from Georgia, and Sen. Chuck Hagel (news, bio, voting record) of Nebraska.