Conservatives nevertheless see the court ruling as a tremendous opportunity.
"If the Republicans use this well, Justice [John] Roberts has all but gift-wrapped the election and repeal for Republicans," Republican strategist Keith Appell said. Asked about Romney's record, which stoked suspicion among conservatives throughout the primary and caucus season, Appell repeated his qualifier: "If Republicans use this well."
Louisiana Gov. Bobby Jindal, a Republican, thought that the more people understood the court decision, the more they will fear the doors opened by the law.
"Reality is going to dawn on people," he said Friday. "It really raises the question, What's next? What's allowable? Taxes on people that refuse to eat tofu or refuse to drive a Chevy Volt?"
All in all, the issue "ends up being a base-raiser for both sides but does not probably alter the campaign dynamic a lot," said Lee Miringoff, the director of the Marist Institute for Public Opinion in New York.
There is a risk for President Obama. "Independents aren't excited about anything that sounds like a tax increase," Miringoff said. But the president gets an advantage in August, when health insurance rebate checks are mailed to millions of people.
Another complication for Republicans: Even people who don't like the law do like some of its provisions. "There's a lot there that people really like," Miringoff said.
In the meantime, Republicans are mobilizing. The Romney campaign reported raising $4.6 million online in the first 24 hours after the court ruling.
In North Dakota, Crossroads GPS, a Republican-allied group, began running ads reminding voters of Democratic Senate candidate Heidi Heitkamp's sympathetic views toward the federal law.
Republicans' chief argument is that the court exposed what party loyalists have said for years: The health-care law is a big tax increase. The law imposes some taxes on wealthy people and penalties on most people who don't obtain coverage by 2014. Democrats had said the penalties weren't taxes. The court said they were.
"Yesterday morning we got powerful confirmation of what may have been the biggest deception of all," Senate Republican leader Mitch McConnell of Kentucky said. "Well, yesterday the court blew the president's cover."
But Massachusetts Institute of Technology economist Jonathan Gruber, an adviser to Romney and Obama while they were crafting their health-care laws, rejected the characterization of the tax issue in a conference call.
"This is not a broad new tax on the middle class," Gruber said, noting that in Massachusetts less than 1 percent of the population pays a penalty of $1,200 rather than purchase health insurance. "As Gov. Romney emphasized, if you don't have health insurance you're a free rider on the care that everyone else is paying for."
White House spokesman Jay Carney had a similar take.
"We're talking about a penalty that would be paid by someone . . . if he's irresponsible and can afford health-care insurance, but doesn't buy it," he said. "In the past, he would have shifted the cost of his care over to you and me and every other American who has insurance and is forced to pay higher premiums because of folks who can afford to buy insurance but don't."
