WASHINGTON -- The Supreme Court has settled the legal argument. Now Americans will find out if President Barack Obama's health care overhaul will work as advertised to give coverage to millions of uninsured people while keeping costs in check, too.

Republicans from presidential candidate Mitt Romney to lawmakers on Capitol Hill will keep pushing for repeal. But the focus will shift from Washington to the states.

Under the law, states play a key role in delivering new health insurance coverage to millions of lower-income and middle-class people.

But Republican-led states have resisted, and the National Association of Insurance Commissioners expects only about half the states to be ready to set up new health insurance markets, slated to open for business in 2014.