One of the main features of the Affordable Care Act is the creation of 50 state-based health-insurance exchanges, online marketplaces where people and small businesses will be able to easily compare competing plans and select the one they prefer. If you're buying insurance on the individual market after the beginning of 2014 (but not if you get your insurance through your employer like most people), your state's exchange is where you'll go. While the federal government establishes a baseline of requirements for what plans offered through the exchange must contain, each state will determine exactly how theirs will work.
But after the ACA was passed, and especially after the 2010 election where Republicans won huge gains at the state level, a lot of states run by Republicans refused to take any action to create their exchanges. Like a Catholic bishop looking at a package of birth-control pills, they retched and turned away, not wanting to sully their hands at all with involvement in President Obama's freedom-destroying health-care plan. But the law also provides that if a state doesn't get around to creating its exchange, then the federal government will just do it for them.
Which is why I've always found the actions of Republicans on this issue puzzling. They all say they hate the federal government, and states can do things better. But in this case, they're letting the federal government take over. Which is probably a good thing.
Let's say you live in Arkansas. Who would you trust to create an exchange that works well and empowers consumers: a state government run by Republicans who think any government involvement in health care is vile, or the Obama administration's Department of Health and Human Services, which has a huge reputational stake in making the Affordable Care Act work as well as possible? Well, you're in luck, because Arkansas has explicitly refused to create an exchange. Plenty of other states with Republican-controlled legislatures have simply dragged their feet in the hopes that either the Supreme Court will strike down the ACA when it hears the case later this year, or that a Republican will win the White House in November and successfully repeal the law (this is a list of where exchanges stand in each state, if you're curious).
Conservative health-care wonks seem to be divided on the issue. Here's one (h/t Sarah Kliff) making exactly the case that I made—if Republicans just ignore this, it'll be turned over to an administration they hate (I just happen to think that's a good thing, while he doesn't). But here's another testifying before the New Hampshire Legislature, telling them not to do anything and hope it just goes away.
This offers a reminder, in case you needed one, that elected officials are not always rational actors. They'll even do things that undermine the principles they hold, for reasons of emotion or pique or false hope. In this case, that means a lot of people living in Republican-dominated states will probably have access to an exchange that works substantially better than whatever their state would have set up. So it'll be a happy ending!