OKLAHOMA CITY (Reuters)—Leaders of the Oklahoma House and Senate said Tuesday they plan to file a lawsuit to block President Barack Obama's reform of the U.S. health care system.

House Speaker Chris Benge and Senate President Pro Tempore Glenn Coffee, both Republicans, said they plan to sue the U.S. Congress, president and U.S. Secretary of Health and Human Services to prevent provisions of the act President Obama signed into law last month from taking effect.

Their announcement follows the refusal earlier this month of Oklahoma Attorney General Drew Edmondson to join a multistate lawsuit led by Florida's attorney general. Mr. Edmondson, a Democrat, said he would join the lawsuit if required by legislative action.

"Our concern is that the attorney general's effort would be lackluster, at best. We have an obligation to our citizens to challenge this unconstitutional bill, which will lead to unprecedented control of a large portion of the U.S. economy," Rep. Benge said in a statement. "The high taxes required in the law will be a burden that we cannot afford."

A resolution authorizing the legislative leaders to file the lawsuit and allowing Oklahoma residents to opt out of mandated health insurance is heading toward final passage.

There have been conflicts in other states, with governors and attorneys general of disparate parties disagreeing on the litigation.

So far, 19 states are participating in the lawsuit filed on March 23 in U.S. District Court for the Northern District of Florida. It claims the reform of the $2.5 trillion U.S. health care system, pushed through by congressional Democrats after months of bitter partisan fighting, violates state government rights in the U.S. Constitution and will force massive new spending on hard-pressed states.

Separately, Virginia has filed a lawsuit, arguing the new law's requirements that most Americans buy health insurance clash with a state law that exempts Virginians from federal fines to be imposed for not owning health insurance.

The U.S. Justice Department has said it will vigorously fight any challenges to the new health care law, which it insists is constitutional. The White House has also said it believes the suits will fail.