The Affordable Care Act's fate has been in limbo since the day it became law. The Supreme Court could have wiped it off the books. A President Romney could've repealed it.

But that's all over now. President Obama’s reelection means that his signature legislative accomplishment, the Affordable Care Act, will fully come into effect.

Obama signs his health-care reform bill into law. (Marvin Joseph/The Washington Post)

That’s what we know for sure. We know a lot less, however, about how that happens. The federal government has never tried to expand private insurance coverage to 30 million Americans, and it will now need cooperation from some very uncooperative states.

The health-care law’s requirement to purchase insurance — and insurance subsidies for millions of Americans — both roll out Jan. 1, 2014. The laundry list of what needs to happen between now and then is pretty massive.

States have to decide whether to set up a health insurance exchange, the marketplace where individuals will shop for health insurance benefits. If they decide against it, the federal government will take over the task.

States must also decide whether they will participate in the Medicaid expansion and extend coverage to all residents under 133 percent of the federal poverty line (about $14,893 for an individual). They also have to figure out who, exactly, earns below that line — a huge technical challenge that requires coordination between federal and state computer systems that don’t usually talk to each other.

Advocacy groups and local officials have to make sure that people actually get enrolled in the health law’s benefits. In their experience with other programs, like the state-based Children’s Health Insurance Program, states have seen that low outreach can mean slow enrollment. This is a lot harder than Medicare, where the federal government simply mailed out enrollment cards to eligible seniors. 

Those are the big-ticket items on the agenda. The timeline to get this all done, meanwhile, is tight. States are supposed to let the Obama administration know by Nov. 16 whether they plan to set up their own health insurance exchange. Only 10 states have passed laws or had governors sign executive orders that commit to doing so. 

Meanwhile, there’s still a lot of opposition to the Affordable Care Act: Exit polls yesterday found Americansremain divided on the law, more than two years after it came into effect. Missouri passed a ballot initiative yesterday that specifically prohibits the state from creating its own health insurance exchange.

The states in orange above have also decided against setting up their own health insurance exchanges: They will let the federal government handle the task.

The states to watch, in the coming months, are the ones in gray: These are the ones that are still on the fence about how aggressively they want to implement. Many of them have hedged about their plans, pointing at the uncertainty with the Supreme Court or the election. Gov. Chris Christie has specifically delayed setting up a New Jersey exchange until after Nov. 6. Gov. Robert Bentley in Alabama has made a similar commitment.

Time’s now up: It’s Nov. 7, and states have some big health reform decisions to make. And they don’t have a lot of time to make them.