The GOP and Federalism

Remember how Republicans always say they believe we should trust states to govern better than the federal government because they are closer to the people they represent? Remember how that was one of the repeated attacks against Obamacare - that the states should be in charge of those sorts of things?

Well one of the main pieces of "Obamacare" is the health insurance exchanges, which each state can set up for themselves. But a state can also choose to let the federal government do it. Surely all those Republican states would prefer to have those run by their state instead of the federal government, right?

Wrong. Here's the breakdown of which states decided to run these themselves, and which ones decided to let the federal government do it, by party lines (found this here):



Is there a reason why Republicans would mostly prefer the federal government to run their state exchanges, other than putting politics over their own supposed principles?