The Affordable Care Act isn’t going to be put up for a referendum. To the extent it matters to voters — and very few people will ever vote on just one issue, health care included — there’s no election where Obamacare could make a difference for over a year.
What will matter is what actual, real consumers find when they think about signing up for health insurance. If those eligible for the exchanges like what they see (and if the interface works, and if they find out about the availability of the marketplaces in the first place), then they’re going to buy insurance, and the system will work pretty well. If not, not.
It’s vaguely possible that political spin might have some effect on expectations. But mostly, people are going to look at prices and make their decision. They’re not going to care whether “everybody knows” that Obamacare makes health insurance more, or less, affordable; they’re going to look at the prices and make their decision. They aren’t going to be voters. They’re going to be consumers.
Getting to the truth underneath the current spin war over health insurance premiums in the exchanges matters if you want to predict what will happen. But as with most such spin wars, it just doesn’t matter. President Obama is exactly right: the best argument for the Affordable Care Act will be successful implementation. And the best argument against it will be if a train wreck really happens.