(CBS News) With his, Rick Santorum leaves behind a socially conservative base that has yet to warm up to Mitt Romney, now the all-but-inevitable Republican presidential nominee.
Leaders in the social conservative movement today praised Santorum's relatively strong campaign and issued a warning to Romney: Embrace Santorum's conservative ideals or risk losing the GOP base in November. While evidence suggests the movement is ready to get behind the eventual GOP candidate to defeat President Obama in the fall, there's still room for staunch conservatives to cause Romney trouble.
Tony Perkins, president of Family Research Council Action, said in a statement that Santorum's campaign lasted as long as it did, in spite of its financial shortcomings, because of Santorum's message of "faith, family and freedom."
"Millions of voters flocked to Rick not because he was a Republican, but because he passionately articulated the connection between America 's financial greatness and its moral and cultural wholeness," Perkins said.
Without mentioning the Romney campaign specifically, the social conservative leader noted that Santorum's "values message generated enthusiasm and drew many new voters into the process. If the Republican establishment hopes to generate this same voter intensity in the fall elections, Santorum voters must see it demonstrate a genuine and solid commitment to the core values issues."
Romney started off as a less-than-ideal candidate for social conservatives, having served as a moderate governor in the blue state of Massachusetts. And his campaign managed to sew more doubt into conservatives' minds when it suggested Romney will recalibrate his positions for the general election, like an "." Thus, winning over Santorum supporters won't be easy for Romney.
"The conservative base cannot be taken for granted," Bill Schneider a public policy professor at George Mason University and a resident scholar at the centrist think tank Third Way, told Hotsheet.
Schneider said social conservatives "are a movement, not a campaign."
"Mitt Romney's running a campaign. A campaign is something you support; a movement is something you believe in, that you belong to," he added.
Having a base that doesn't trust him could create complications for Romney, Schneider said, much in the way the conservative base divided the GOP at the 1992 Republican convention -- ultimately hurting President George H.W. Bush's re-election campaign.
Conservative activist Richard Viguerie told CBS News he was disappointed to see Santorum bow out and that it's too early for him to say whether he will support Romney. There are a lot of hard feelings towards Romney, he said, adding that "the next six moves are up to him... We need to hear from Gov. Romney."
Viguerie said Santorum still "has an opportunity to provide major leadership for the conservative cause" and could serve as a bridge between Romney and social conservatives.
"I think a lot of conservatives would welcome having one articulate voice speaking to the Romney campaign for us," he said. "He's that only person that could fill that role right now."
For most conservatives, the main objective remains defeating President Obama, and the anti-abortion rights group the Susan B. Anthony List said in a statement today it remains committed to that goal, even with the group's preferred candidate out of the running.
"The political muscle of the pro-life movement will be critical to defeating President Obama in November," SBA List president Marjorie Dannenfelser said in a statement, noting that Santorum's campaign demonstrated that voting bloc's influence.
Maggie Gallagher, president of the Culture War Victory Fund, endorsed Santorum early on but today called for the GOP to unify behind Romney.
"For social conservatives, especially Christian conservatives, the race between President Obama and Governor Mitt Romney is not a close call," she said in a statement. "A pro-life, pro-marriage, pro-religious liberty president is priority number one. It's clear it's going to be a tough fight and a close election, and we need every man and woman on board to win."
Still, the social conservative base isn't the only movement Santorum leaves behind -- he also served at times as the candidate for the Tea Party movement. Gary Bauer, president of American Values, stressed in a statement that Santorum's appeal extended beyond values issues.
"His message of smaller government and a strong national defense resonated with the heart of the Republican Party," Bauer said of Santorum. "His contribution to the debate has made the GOP stronger, and will contribute to the end of the Obama Administration this November."
CBS News producer Caroline Horn contributed to this report.