The National Federation of Independent Business said in the appeal that the entire law should be invalidated because Congress exceeded its powers in adopting a key provision that requires Americans to buy health insurance or face a penalty.

It asked for a quick resolution in the Supreme Court's upcoming term, which begins next week and lasts through June 2012. The Obama administration also is expected to ask the Supreme Court to decide the healthcare law.

The National Federation of Independent Business, a Tennessee-based group representing 350,000 U.S. small businesses, had joined 26 states, led by Florida, in challenging the law.

A U.S. appeals court in Atlanta in August declared unconstitutional the individual insurance requirement, but refused to strike down the entire law.

While the business group appealed the case to the Supreme Court, Florida and the other states have yet to say whether they would bring their own separate appeal to the highest U.S. court.

The ruling by the appeals court in Atlanta conflicted with rulings by other appeals courts that have upheld the law or have rejected legal challenges, including a lawsuit by the state of Virginia that was dismissed earlier this month on procedural grounds.

The law, passed by Congress and signed by Obama in 2010 after a bruising political battle, is expected to be a major issue in the 2012 elections as Obama seeks another four-year term. The major Republican presidential candidates oppose it.

EXPANDING COVERAGE

Obama, a Democrat, has championed the law as a major accomplishment of his presidency and as a way to try to slow soaring healthcare costs while expanding health insurance coverage to the more than 30 million Americans without it.

The Supreme Court long has been expected to have the final word on the law's constitutionality. The dispute has important legal, political and financial implications for companies in the healthcare field.

"It is now imperative that the Supreme Court rule on whether the entire law can stand without the mandate," said Karen Harned, executive director of the Small Business Legal Center of the National Federation of Independent Business.

"The sooner the court takes up this case, the sooner small businesses and individuals will know whether they will have to bear the full weight, financially and economically, of this bad law," she said in a statement.

Legal experts have said the Supreme Court most likely will be closely divided on whether the individual mandate requiring insurance purchases exceeded the power of Congress.

They said the ruling on the nine-member court, closely divided with a conservative majority and four liberals, could come down to Chief Justice John Roberts and Justice Anthony Kennedy.

The Obama administration earlier this week said it decided against asking the full U.S. Appeals Court for the 11th Circuit to review the August ruling by a three-judge panel of the court that found the insurance requirement unconstitutional.

That decision cleared the way for the administration to go to the Supreme Court. The administration has said it believes the law will be upheld in court while opponents say it represents an unconstitutional encroachment of federal power.