As the Supreme Court prepares to rule on the constitutionality of President Obama’s health-care overhaul, Mitt Romney laid out an alternative on Tuesday that would make the health insurance system more like a “consumer market.”

Addressing supporters in Orlando, Romney fleshed out a plan that he proposed earlier, one that would apply free-enterprise principles to the nation’s health-care system rather than operate it like a “government-managed utility,” letting competition drive down prices and increase quality. He also vowed to divert federal Medicaid money and other federal funding to state governments, making them responsible for covering the uninsured. And he promised that his plan would help cover people with preexisting conditions, one of the more popular components of Obama’s law.

Romney attacked what he and other Republicans have labeled “Obamacare.” The presumed GOP presidential nominee said that if the Supreme Court does not overturn the law in full, he would work to repeal whatever remains of it on his first day as president by granting a waiver to all 50 states to opt out of the legislation’s restrictions.

Romney likened the health-care system under the Affordable Care Act to “a big government-managed utility” and argued that the law is casting a dark cloud over the nation’s anemic economic recovery.

“It’s not only bad policy and bad for middle-income families and bad for small business, it’s simply unaffordable,” Romney said. “And so, the right course for us is to make sure that the next president of the United States repeals Obamacare and replaces Obamacare.”

The Obama campaign hit back at Romney’s policy view with a statement saying he “wants to take us backward on health care.”

“Mitt Romney promised that if he’s elected, insurance companies will be able to discriminate against Americans with pre-existing conditions, charge women higher premiums than they charge men for the same coverage, and kick young adults off their parents’ plans when they graduate high school or college,” campaign spokeswoman Lis Smith said in the statement. “For too long, American families have faced a choice between going bankrupt to afford the care they need or going without that care at all, and Mitt Romney wants to take us back to that time.”

Romney first laid out a plan to replace the health-care law in a speech in Michigan in spring of last year, before he formally began his campaign. But he avoided detailed discussions of health care during the Republican primaries, partly because the Massachusetts law he championed and signed as governor is so similar to the federal law and drew sharp criticism from many conservatives in his party.

With Tuesday’s speech, delivered in a warehouse here, in front of a banner reading “Repeal & Replace Obamacare,” Romney for the first time since the Michigan speech detailed some of his health-policy positions.

He said that his top priority is to care for the nation’s uninsured but that he would make states responsible for providing that service.

“I believe that states have responsibility to care for people in the way they feel best,” Romney said. “It’s important for us, in my view, to make sure that every American has access to good health care.”

But the Obama campaign pushed back, saying that Romney’s proposed budget cuts to Medicaid would underfund such care and give state governments no choice but to leave people uncovered.

Romney said he wants to make the nation’s health-care system more like a consumer market, likening it to the tire, automobile and air-filter markets, which, he said, keep costs down and quality up. To do so, he said, he would allow individuals and small businesses to buy insurance coverage with the same tax advantage that larger businesses enjoy and to purchase insurance across state lines or join organizations to give them bargaining power with insurers.

“We can get health care to act more like a consumer market, and if we do that and we stop making it like a big government-managed utility, we’re going to see better prices, lower costs and better care,” Romney said. “It’s happened everywhere we’ve applied consumer-market principles. Free enterprise is the way America works. We need to apply that to health care.”

Conservatives have long proposed letting people buy insurance across state lines, but the Obama campaign said that would erode consumer protections and empower insurance companies.

Romney also said his plan would help cover people with preexisting conditions if they lose or change their jobs, although Americans already have been guaranteed such coverage since the 1990s under the COBRA law.

“Let’s say someone has been continuously insured and they develop a serious condition, and let’s say they lose their job or they change jobs, they move and they go to a new place,” Romney said. “I don’t want them to be denied insurance because they’ve got some preexisting condition.”