WASHINGTON – The Supreme Court said Monday it will hear a challenge to the health-care overhaul act passed in 2010, with a decision on President Obama’s most controversial domestic achievement likely to come in the summer of his re-election campaign.

The court said it will decide whether the Affordable Care Act exceeded Congress’s power by requiring almost all Americans to have health insurance by 2014 or pay a penalty, a powerful constitutional question that will likely make it the court’s most high-profile ruling since Bush vs. Gore in 2000.

As a mark of the importance of the case to the court headed by Chief Justice John G. Roberts Jr., justices said they will hear 5 1/2 hours of oral arguments on the constitutional question and related issues. Oral arguments will most likely be held in March over one or two days, with a decision expected before the court recesses in late June.

The White House welcomed the court’s announcement. “We know the Affordable Care Act is constitutional and are confident the Supreme Court will agree,” White House spokesman Dan Pfeiffer said.

Senate Republican leader Mitch McConnell (Ky.) countered that the massive law is both unpopular in polls and with voters.

Sen. Olympia Snowe, R-Maine, said that she was “pleased” that the high court took the health care case.

Snowe was the only Republican on the Senate Finance Committee to vote in favor of the health care bill when it was approved by the committee in October 2009, but voted against the bill on the Senate floor in December 2010.

Snowe said in a statement Monday that she voted against the final bill on the Senate floor because “it was a massive expansion of government regulation, taxes, and spending that dismantled and undercut the vital market-based reforms Maine families and small businesses desperately needed to enhance their access to quality and affordable health care options.”

But Rep. Chellie Pingree, D-1st District, said in a statement that, “The health care reform law has already begun to benefit millions of Americans — young people who stay on their parents’ plans or seniors getting discounts on prescription drugs are just a couple of examples. I’m confident the Supreme Court will uphold the health care reform law.”

Rep. Mike Michaud, D-2nd District, did not predict an outcome but said it’s important for the Supreme Court to tackle the issue since several lower courts have disagreed.

Accepting appeals from a decision by the U.S. Court of Appeals for the 11th Circuit in Atlanta — the only appeals court to say the law was unconstitutional — justices said they would consider:

• Whether Congress was acting within its constitutional powers by requiring all Americans have at least a basic form of health insurance by 2014. Those who do not would be required to pay a penalty on their 2015 income tax returns.

• Whether other parts of the law can go forward if the so-called individual mandate is found unconstitutional.

Lower courts have differed on the question, but the administration says the law’s more popular features, such as prohibiting insurance companies from denying coverage to those with preexisting conditions, cannot work financially without the mandate that all join the system.

• Whether Congress is improperly coercing states to extend Medicaid, the subsidized health care for the poor and disabled, to those with incomes of 133 percent of the federal poverty level.

Medicaid is a shared expense of the federal and state governments, and the federal government would pay 100 percent of the additional cost through 2016. The percentage would decline after that.

• Whether the issue is ripe for a decision.

Some lower court judges have said the penalty for not having insurance is the same as a tax, and thus cannot be challenged until someone actually has to pay it in 2015.

Jonathan Riskind, MaineToday Media Washington Bureau Chief, contributed to this report.