But if the court strikes any part down, the defeat for Obama could mean uncertainty for both parties.
Congressional Republicans intend to seek quick repeal of any parts of the health care law that survive the court's ruling, but they don't plan to push replacement measures until after the November elections. Obama and congressional Democrats haven't said what they would do in the event the court rejects the law.
"We remain confident that the Affordable Care Act is constitutional and we are ready for whatever decision is rendered by the Supreme Court," White House press secretary Jay Carney said.
The high court's decision to throw out key provisions of Arizona's crackdown on illegal immigrants guarantees that the issue has a high profile in the elections as Obama tries to protect his party's substantial lead among Hispanics, and Republicans seek to narrow the polling advantage.
Democrats howled that the Arizona immigration law decision clears the way for racial profiling, while Republicans said the decision upholds states' rights to enforce their own immigration policies. Both sides insisted that Congress needs to pass a long-term immigration policy that applies to the estimated 11 million people in the country illegally, an issue that has divided lawmakers for years.
"No American should ever live under a cloud of suspicion just because of what they look like," said Obama, who won two-thirds of the Latino vote in 2008 and recently issued a directive that protects young immigrants who came illegally to the United States as children. Obama pledged in 2008 to push for passage of comprehensive changes in immigration laws, but the effort stalled in Congress and Obama turned his attention to addressing the economy and pressed ahead with passing an overhaul of health care laws.
Romney, campaigning in Arizona on Monday, blamed Obama for lack of action on immigration. He also said states have the right to secure their borders, "particularly when the federal government has failed to meet its responsibilities."
Within a few hours of the court's ruling on immigration, Republican Rep. John Mica, who's in a tough GOP primary race in Florida against Rep. Sandy Adams, asked his constituents in a letter to "stand with me for Arizona's state rights."
"P.S.," Mica added. "Will you consider making a contribution to my campaign today?"
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