Even as U.S. President Barack Obama signed his health care overhaul into law on Tuesday, opponents were vowing to repeal the historic legislation.

U.S. President Barack Obama (C) signs the healthcare reform bill at the White House in Washington D.C., capital of the United States, March 23, 2010. [Zhang Jun/Xinhua]

So far, more than a dozen U.S. states' attorneys-general have announced their plans to file suit against the federal government in order to halt one of the bill's provisions, which requires all Americans to buy health insurance or pay a fine. They contend the mandate is unconstitutional, and many opponents fret that the rule greatly expands the power of the Internal Revenue Service.

But the question remains whether a lawsuit can successfully repeal the controversial legislation.

Don't miss?

14 states file lawsuits over healthcare bill

Obama signs healthcare bill

U.S. healthcare reform

"I think it is very unlikely that the provision will be reversed by the courts," said Norman Ornstein, congressional scholar at the American Enterprise Institute, a think tank. "There is a general reluctance to reverse Congress."

He added that a large part of the effort for repeal amounts to politicking.

David Kendall, a health policy expert at Third Way, another think tank, said the move to sue the federal government over such a rule is unprecedented.

Still, he doubts the challenge will result in a repeal, and maintained that the legislation is not unconstitutional, as the plaintiffs claim.

The federal government has the authority to write such legislation and states have long required drivers to purchase auto insurance, he said, although opponents of that argument contend that driving is a voluntary act and not comparable to the issue of health insurance. He added that residents of Massachusetts are required by law to carry health insurance.

"It's largely another way of representing the political debate on the issue. And opponents won't be satisfied until they exhaust all the options," he said.

Indeed, Republicans are stepping up to denounce the legislation.

Prominent GOP members -- such as Reps. Steve King, R-Iowa, and Michele Bachmann, R-Minn., and Sen. Jim DeMint, R-S.C. -- are introducing legislation to reverse Obama's reforms.

"There's no fixing the government health care takeover Democrats forced through on Sunday. It must be repealed," wrote Demint in an opinion piece in USA Today. "The plan will explode the national debt, raise 569.2 billion dollars in new taxes, force taxpayers to fund abortions, and impose unconstitutional mandates on every American."

Gov. Mitt Romney, who campaigned for the Republican nomination for president in 2008, called for a repeal of the legislation, as did former vice presidential candidate Sarah Palin, who many suspect will make a run for the presidency in 2012.

Virginia Attorney General Ken Cuccinelli also plans to sue the federal government.

"The unconstitutional aspect is that the individual mandate on Americans that they must buy health insurance or face penalties overreaches the authority of the Congress under the commerce clause," he said on Fox's "On the Record" on Monday.

"Buying health insurance can be said to be an act in commerce. Not buying health insurance, doing nothing, is not an act in commerce. And it has never before been included in a federal law to mandate that individual citizens buy something from some other entity, another citizen, another company," he added.

Experts noted the lawsuits will not slow the new law's implementation and the Department of Health and Human Services is gearing up to put the legislation into effect.

Still, the move has gained public support, and a poll released on Tuesday from polling company Rasmussen found that 49 percent of U.S. voters favor their state suing the federal government in a bid to halt the provision that requires everyone to buy health insurance.

Thirty-seven percent disagree and oppose their state suing to challenge that requirement and 14 percent remain undecided, the poll found.

A CNN poll taken over the weekend found that 59 percent of Americans oppose the new legislation and 39 percent favor it, with 2 percent expressing no opinion.