Republican presidential candidate Rick Santorum appeared outside the Supreme Court on Monday as the justices heard arguments over whether President Barack Obama's overhaul of the nation's health care system is constitutional.
Also Monday, Mitt Romney picked up some conservative endorsements while campaigning in California.
In Washington, Santorum pressed his own argument that he's the best candidate — and rival Romney is the worst — to challenge Obama on the health care issue in the fall.
"There's one candidate who's uniquely disqualified to make the case. That's the reason I'm here and he's not," Santorum told reporters outside the Supreme Court as protesters behind him chanted, "Health care is a right."
"This is the most important issue in this election," he said.
While Romney says he would fight to repeal Obama's health care law, Santorum says Romney essentially is disqualified because he put in place a similar law in Massachusetts when he was governor, including a requirement that all residents buy health insurance.
"This was a disaster in Massachusetts," Santorum said.
Public polls, however, suggest that the vast majority of Massachusetts residents support the state health care system, which Romney signed into law in 2006.
A similar so-called "individual mandate" in Obama's law has drawn the ire of conservatives, including Santorum. And that's a key argument for opponents who this week are asking the high court to strike down the law as unconstitutional.
"If we make this the central issue in the campaign and we're successful, there's no doubt that Obamacare will be repealed in one form or another," Santorum said. "That not going to be the case with Governor Romney."
Santorum won Louisiana's primary Saturday but continues to lag behind Romney.
Ryan Williams, a spokesman for Romney, dismissed the comment.
Romney announced support Monday from Utah Sen. Mike Lee, an early tea party supporter who ousted a longtime incumbent Republican. The GOP presidential front-runner also earned backing from California Rep. Kevin McCarthy, the third highest-ranking House Republican, and from Al Cardenas, head of the American Conservative Union.
The endorsements add to a growing chorus of Republican stalwarts and conservative leaders who are calling on the party to unite behind Romney so the GOP can begin to focus on the general election.