Then came the remarkable late surge in enrollment. Did the pessimists face tough questions about why they got it so wrong? Of course not. Instead, the same people just came out with a mix of conspiracy theories and new predictions of doom. The administration was “cooking the books,” said Senator John Barrasso of Wyoming; people who signed up wouldn’t actually pay their premiums, declared an array of “experts”; more people were losing insurance than gaining it, declared Senator Ted Cruz of Texas.

But the great majority of those who signed up did indeed pay up, and we now have multiple independent surveys — from Gallup, the Urban Institute and the Commonwealth Fund — all showing a sharp reduction in the number of uninsured Americans since last fall.

I’ve been seeing some claims on the right that the dramatic reduction in the number of uninsured was caused by economic recovery, not health reform (so now conservatives are praising the Obama economy?). But that’s pretty lame, and also demonstrably wrong.

For one thing, the decline is too sharp to be explained by what is at best a modest improvement in the employment picture. For another, that Urban Institute survey shows a striking difference between the experience in states that expanded Medicaid — which are also, in general, states that have done their best to make health care reform work — and those that refused to let the federal government cover their poor. Sure enough, the decline in uninsured residents has been three times as large in Medicaid-expansion states as in Medicaid-expansion rejecters. It’s not the economy; it’s the policy, stupid.

What about the cost? Last year there were many claims about “rate shock” from soaring insurance premiums. But last month the Department of Health and Human Services reported that among those receiving federal subsidies — the great majority of those signing up — the average net premium was only $82 a month.