Gov. Nikki Haley and the state’s Republican leaders have pledged that they will oppose “the implementation of Obamacare.” But that horse already has left the barn.

Last year’s decision by the U.S. Supreme Court that most of the federal Affordable Care Act is constitutional and the re-election of President Barack Obama practically ensure that all or most of Obamacare will be implemented despite efforts by opponents to block it. The only choice for states is whether to go along and act in the best interests of their residents or to engage in a largely symbolic protest that ultimately could cost them billions of dollars.

Specifically, the issue centers on whether states will join with the federal government in expanding Medicaid coverage for the poorest residents. Under provisions of the Affordable Care Act, anyone earning less than 138 percent of federal poverty level – about $15,000 for individuals and $26,000 for a family of three – would be covered by the expanded Medicaid program.

But while the Supreme Court upheld much of the Affordable Care Act, justices ruled that the federal government did not have the authority to require states to expand Medicaid coverage beyond current levels. Thus the state gained the right to opt in or out of the expansion.

Haley and most GOP legislators oppose the expansion, saying the state can’t afford it. Many of the state’s Democrats, however, say the state can’t afford not to take advantage of the offer.

Under the provisions of the act, the federal government would pay 100 percent of the cost of the expansion for the first three years, gradually dropping to 90 percent in 2020. That means the feds would pay around 93 percent of coverage costs on average over the next decade or so.

Proponents of the expansion also note that extending access to medical coverage for hundreds of thousands of poor residents would encourage them to go to doctors for preventative care and early intervention, which would improve their health and save the system money in the long term. By contrast, not expanding Medicaid coverage would simply preserve the status quo, in which uninsured residents either go to already overburdened free clinics or federal health centers, or use hospital emergency rooms for primary care.

Increased spending on medical care for the poor would provide a modest economic stimulus for the state. The money would help create new jobs for nurses and other health care providers, manufacturers and sellers of medical supplies and all those in the medical care chain.

And not accepting federal dollars to expand Medicaid means that South Carolina’s taxpayers would help subsidize medical care for poor residents of other states. South Carolina wouldn’t benefit at all from those tax dollars.

South Carolina not only is near the top in incidence of most chronic diseases, it also is near the bottom in the percentage of residents covered by health insurance. The most recent accounting indicates that 17 percent of South Carolinians – or more than 730,000 – are uninsured.

Those people will continue to get sick, have accidents and require routine medical care whether the state helps provide them with access to insurance or not. And the question is not whether residents of the state will continue to pay for that care but how they will pay for it – through Medicaid or through higher health care costs for all incurred by using emergency rooms for primary care.

While opponents of expanding Medicaid say they worry that the state can’t afford it, another compelling reason they oppose it is their hostility toward Obamacare. Again, though, the Affordable Care Act is the law of the land.

The obstinate refusal to acknowledge that and take advantage of a provision that would benefit the state and help provide cheaper medical coverage to hundreds of thousands of residents is irrational.