DALLAS (AP) — The federal government may have to implement a major provision of President Barack Obama's health care overhaul in Texas since the state's conservative leaders are steadfastly opposed to it. But one state agency has fulfilled parts of the law and said it's prepared to move forward if the law is upheld by the U.S. Supreme Court.

Gov. Rick Perry and other Republican leaders have blasted the measure since Obama signed it in March 2010, though they've offered few solutions on how to drive down health care costs if the high court revokes the law in a ruling expected by Thursday. A quarter of Texas' population — about 6.2 million people — is uninsured.

Texas, among several states challenging the law, has lagged in implementing some of the law's provisions, including setting up a state health care exchange that would serve as an insurance marketplace for people and small businesses to buy coverage. Texas received a federal grant to help plan the network, but has shown little evidence of implementing the plan.