Rick Santorum invokes Ronald Reagan at Jelly Belly factory in Fairfield, California FAIRFIELD, Calif. - Republican leaders and voters, frustrated by their party's prolonged presidential contest, are increasingly coalescing behind front-runner Mitt Romney. Yet Rick Santorum on Thursday urged conservatives not to forsake their principles under pressure. He did so by conjuring the memory of Ronald Reagan, still the conservative icon, at an oddly symbolic place: the jelly bean factory that created the former president's favorite treats. "Let them know, conservatives all across this country have not given up the fight, we're not going to concede to the moderate establishment who wants to convince everybody that it's over, it's time to go away," Santorum told about 200 supporters at the Jelly Belly factory in a town halfway between San Francisco and Sacramento. He alluded to Reagan's favored policy trio of free enterprise, a strong defense and conservative social policies, saying, "We as conservatives need to stand up and fight for a candidate who can win this general election, who stands solidly, firmly on the 'three-legged stool' that brought the Reagan coalition together." Santorum's brushback of party leaders came the same day that former President George H.W. Bush endorsed Romney, and after similar nods from Florida Sen. Marco Rubio and former Florida Gov. Jeb Bush. All three expressed concern that the party's prolonged nomination battle was harming their nominee's chances against President Obama in the fall. Santorum declined to comment on the endorsements while shaking hands with supporters after his speech. Like all of the GOP candidates, Santorum speaks glowingly of the late president, but his remarks on Thursday had special resonance because of the locale. Multicolored murals of Reagan and his wife, Nancy, made of jelly beans, hung outside the room where Santorum spoke. The former Pennsylvania senator tried to paint himself in the image of Reagan, as a true believer in limited government, conservative social values and a strong national defense - but one who is opposed by the party elite because he refuses to waver. They're asking you, people of principle, to compromise your principles and to be for someone who is less corely convicted than Ronald Reagan because we need to win. My question is, 'Win what?' " he said. Every time we run someone that the moderate establishment of the Republican Party said we need to win, we lose. Because Americans don't have a clear choice. They don't have a vision for someone who actually believes and who dramatically, decisively lays out a vision for the American people to inspire and lift up and get people, like Reagan did, to believe in themselves. While the speech was billed as a major foreign policy address, Santorum spent much of his time castigating Romney for failing to toe to Reagan's positions - for example with the implementation of Romney's state healthcare law while Massachusetts governor and his past support of abortion rights. Santorum was incredulous that Romney had been running ads in Wisconsin that imply Santorum supported abortion rights while in Congress. "I was out there leading the charge while Gov. Romney was contributing money out of his own checkbook to Planned Parenthood," Santorum said. He noted that Romney, in his race for the Senate in 1994, ran as a moderate and said that he was not seeking to return to the Reagan-Bush era. Santorum described himself as a consistent conservative whose beliefs were "written on his heart." Santorum mocked an incident last week in which a Romney advisor said the candidate would be able to reset his policies for the general election, as if using a children's toy. Romney said after the Etch A Sketch flap that he's going to run as a conservative in the fall. I'm not going to run as a conservative. I am a conservative," Santorum said, and the crowd roared. On foreign policy, Santorum's remarks were more focused on Obama. Noting an incident over the weekend in which the president was heard telling Russian leader Dmitry Medvedev that he would have greater flexibility to discuss a missile defense system after the election, Santorum said the president had put his electoral interests above the nation's security. "Of all of the failings of this administration, of all of the failings, perhaps the greatest is on national security, and folks, that's saying something," he said. This president has alienated ally after ally, isolated them, particularly of course the state of Israel. They've encouraged, encouraged our foes.