By DARLENE SUPERVILLE

WASHINGTON (AP) _ President Barack Obama is aiming to use the momentum from a recent Supreme Court victory for his health care law to change the conversation from talk about undoing his signature domestic achievement to talk about how to improve it.

Obama was headed to the Nashville, Tennessee-area on Wednesday to discuss ways to improve the Affordable Care Act, including by extending Medicaid coverage to more low-income people. Tennessee is one of the few states where a Republican governor has tried to expand coverage for the poor.

Obama wants to change the conversation after the U.S. Supreme Court last week turned away a major challenge to the law that would have endangered health insurance for millions of Americans. In a 6-3 decision, the justices upheld federal financial aid to millions of low- and middle-income Americans to help pay for insurance premiums regardless of where they live.

Obama declared after the ruling that the law is “here to stay.” He cited progress under its provisions, but said “we’ve still got work to do to make health care in America even better,” including by helping consumers make informed choices about their medical care, increasing the use of preventive care, improving the quality of hospital care and reducing costs.

Just over 80 percent of people under age 65 had health insurance when Obama enacted the law in 2010. Since then, the share has risen to about 90 percent.

The administration would like to boost health care enrollment even further by helping the remaining uninsured get coverage. But achieving the goal largely depends on roughly 20 states, most led by Republican governors and including some heavily populated states like Florida and Texas, that have refused Obama’s offer of billions of dollars in federal money to pay to expand their Medicaid programs.

Obama has said in recent days that convincing these holdout governors will be important.

“If we can get some governors that have been holding out and resisting expanding Medicaid primarily for political reasons to think about what they can do for their citizens who don’t have health insurance but could get it very easily if state governments acted, then we could see even more improvement over time,” Obama said at the White House on Tuesday.

Next year is the final year that Washington will offer full funding to states to pay for the expansion. After 2016, the federal share will begin to gradually decline, and that will leave states with expanded Medicaid programs responsible for picking up more of the costs.

Republican lawmakers said the Supreme Court decision doesn’t change the fact that the law is flawed and should be repealed. No Republicans voted for the law in 2010.

“We will continue our efforts to repeal the law and replace it,” House Speaker John Boehner, R-Ohio, said last week.

Tennessee Gov. Bill Haslam, a Republican, has proposed extending Medicaid coverage to 280,000 low-income state residents, but the plan failed during a special session of the Republican-controlled Legislature earlier this year. It was revived during the subsequent regular session, but failed in committee.

Tennessee U.S. Rep. Jim Cooper, a Democrat, is among state officials calling on state lawmakers to reconsider Haslam’s plan in light of the U.S. Supreme Court ruling.