WASHINGTON -- The U.S. Supreme Court is expected to rule Thursday on President Barack Obama's health care overhaul in a huge case with repercussions for the U.S. presidential race.

The health care law is Obama's biggest legislative accomplishment as president. It is almost universally disliked by Republicans, including Mitt Romney, Obama's likely rival in the November election. Romney has vowed to overturn the law if elected.

Democrats say Obama's plan will extend health care to millions of Americans now lacking insurance. Republicans see it as government overreach, especially a provision requiring most Americans to obtain insurance coverage.

Thursday will be the court's last day in session before its summer recess.