The Web site. (Andrew Harrer/Bloomberg)

David K. Jones is an assistant professor at the Boston University School of Public Health. Nicholas Bagley is an assistant professor of law at the University of Michigan.

Any day now, the Supreme Court will announce its decision in King v. Burwell, the latest high-stakes fight over the Affordable Care Act. If the government loses, more than 6 million residents of the 34 states that declined to establish their own health-care exchanges could lose subsidies that help them purchase insurance.

In principle, those 34 states could restore subsidies by creating their own insurance exchanges. Political leaders will certainly come under intense pressure to do so, although time is short to get an exchange up and running for 2016. Given the potential need for swift action, do the states have contingency plans in place? Could they move quickly in the wake of an adverse decision?

To investigate these questions, we undertook, with financial support from the Commonwealth Fund, a study of five states that could lose tax credits: Florida, Michigan, New Hampshire, North Carolina and Utah.

What we found was both striking and worrisome. Dozens of interviews conducted by our research team with political leaders, agency officials and advocacy organizations in those states indicate that the states are almost completely underprepared for the Supreme Court’s decision in King. As North Carolina Gov. Pat McCrory (R) said in March, “There’s no B plan.

The Affordable Care Act is facing another challenge at the Supreme Court in King v. Burwell, which deals with subsidies for health insurance. The case could cut out a major provision of Obamacare, causing the law to unravel. Here’s what you need to know about the case. (Julie Percha/The Washington Post)

The difficult politics surrounding health-care reform make it hard for either Democrats or Republicans to engage in serious planning. Democrats don’t want to get ahead of the Obama administration or signal to the Supreme Court that a ruling will not have major consequences. Republicans, who control at least one house in the legislature in all but three of the 34 states that use the federal exchange, told us that while they fear being blamed if people lose insurance, they also worry about the political repercussions of supporting any element of Obamacare, including the creation of a state exchange.

The safest approach is to sit tight. Pennsylvania and Delaware are the only states whose leaders have indicated they will create a state exchange if the government loses in King. An exchange bill is currently before the Maine Senate after having passed the House. Of the states we examined, New Hampshire is best positioned to move quickly after the ruling comes down in King. Some policymakers there hope to pass a law — nicknamed the “magic wand” — that simply declares the federal Web site to be a state-based exchange within New Hampshire’s borders.

In each of the five states, political resistance to new exchanges is expected to be fierce. The speaker pro tempore in the Florida House of Representatives, for example, told us that “Florida has no desire to create a state-based exchange,” even if the government loses in King. Republicans’ recent rejection of Medicaid expansion suggests that they aren’t bluffing.

Legislators in Michigan believe that any discussion of a state exchange could spur a resurgence of the tea party, whose opposition doomed Republican Gov. Rick Snyder’s original effort to create an exchange. And the leader of the North Carolina Senate is an ardent foe of the Affordable Care Act.

Timing is another concern. State policymakers don’t know when they would need to make tough decisions. When will the court’s ruling go into effect, and when will people lose coverage? Will Congress pass a temporary patch? If so, how long will it last?

Policymakers also expressed frustration with the Obama administration’s silence about its plans. Most states expect the administration to make it easier for them to transition to state exchanges. But they are reluctant to make concrete plans when they don’t know what the federal government expects of them.

In the states that have failed to lay the groundwork, it will probably be impossible to set up an exchange in time for 2016. Open enrollment for next year is scheduled to begin this fall, meaning insurance companies proposed rates to state regulators months ago. Even with the full-throated support of the political establishment, many leaders said they would need at least 12 to 18 months to create a new exchange.

Compounding the timing challenge, only one legislature of the five states we studied (Michigan), and eight of the 34 affected nationally, will be in session after the court’s ruling. Although a special session appears likely in Utah, creating an exchange may not be on the agenda. It’s far from clear that special sessions will be called elsewhere.

There is some reason for mild optimism. Moderate Republicans, we were told, might support a state exchange if the alternative is that many of their constituents lose their coverage. And the governor in each of the five states is expected to be more supportive of creating an exchange than their legislatures.

But the bottom line is grim. The states aren’t prepared for King, and any debates over whether to create state exchanges will be turbulent and difficult. In the meantime, millions of people stand to lose their health insurance.

David K. Jones is an assistant professor at the Boston University School of Public Health. Nicholas Bagley is an assistant professor of law at the University of Michigan.