Some of Mitt Romney's former foes have yet to endorse him as the Republicans' presidential nominee. A look at what each wants:
_ RICK SANTORUM
The former senator from Pennsylvania campaigned hard against Romney and the health care overhaul he signed into law as Massachusetts governor. Conservatives cast it as a precursor to Democrats' national plan and Romney has vowed to repeal it. Santorum advisers say he will not back Romney until he is convinced that Romney is committed to upending it, as well as ensuring conservatives' views are represented in the party's platform and in Romney's campaign.
_ NEWT GINGRICH
The former House speaker leaves the GOP campaign with his reputation battered and his wallet empty. He is looking to repair his standing in the party as the intellectual heavyweight and for an opportunity to push conservative policy goals. Romney, now the party's leader, could afford him that platform. Gingrich is also carrying more than $4.5 million in debt and would welcome Romney urging his supporters to help pay it down.
_ RON PAUL
The congressman from Texas is still in the race and hasn't yet recognized Romney as the party's nominee. He is pushing a libertarian message of ending the Federal Reserve, returning the country's currency to the gold standard and reducing the United States' involvement around the globe. Romney disagrees with those positions, probably precluding an endorsement from Paul.