Fourteen US states filed a lawsuit Tuesday challenging the constitutionality of health care reform just moments after President Barack Obama signed the historic bill into law.

"This lawsuit should put the federal government on notice that Florida will not permit the constitutional rights of our citizens and the sovereignty of our state to be ignored or disregarded," said Attorney General Bill McCollum.

McCollum, a Republican who is running for governor in the upcoming election, led the charge to challenge a provision that would require most people to buy health insurance or else pay a fine.

"This is not a partisan issue," he told reporters. "It's a question for most of us in the states of the cost it is to our people and to the rights and freedoms of the individual citizens."

He was joined by the Republican attorneys general of South Carolina, Nebraska, Texas, Utah, Alabama, Colorado, Pennsylvania, Washington, Idaho, South Dakota and Michigan, and the Democratic attorney general of Louisiana.

Virginia filed a separate suit on Tuesday asking a federal judge to invalidate the entire health care reform act because the federal government overstepped its authority in requiring people to buy health insurance.

"There has never been a point in our history where the federal government has been given the authority to require citizens to buy goods or services," Virginia Attorney General Ken Cuccinelli said in a statement.

Obama's Republicans foes have waged a political war on the historic health care overhaul and have vowed to repeal it should they retake the House and Senate in November mid-term elections.

The governor of Idaho signed a bill into law last week blocking federal mandates requiring individuals in his state to purchase health insurance and a similar bill was passed in Virginia.

Some 34 other states have either filed or announced their intention to file similar legislation, according to the National Conference on State Legislatures.

White House spokesman Robert Gibbs said Monday it's typical for "big pieces of legislation" to face legal challenges but there is "pretty longstanding precedent on the constitutionality of this."

The White House does not believe their opponents "will be very successful," he told reporters.

But the question of whether the federal government can require people to buy health insurance will likely head to the Supreme Court, said Jonathan Siegel, a law professor at George Washington University.

"Is the bill constitutional? I think the answer is yes, but it's not a 100 percent slam dunk," Siegel said.

The federal government is granted the right to regulate commerce and is also granted whatever "necessary and proper" powers needed to do so, Siegel said.

While it's clear that the only way to get private insurance companies to stop discriminating against sick people is to make sure that people don't wait until they get sick to buy it, it's not completely clear if the government's powers extend to requiring people to buy insurance, he said.

The question of whether state legislators can try to block the bill has a much more straightforward answer, he said.

"State law is irrelevant," Siegel told AFP.

"Where state and federal law conflict, federal law wins."