[T]he largest effect [on the reduction in the uninsured] comes, not from the subsidies, nor from the mandate, nor even from the Medicaid expansion. The largest effect was due to that 'woodwork effect' -- about 44 percent.... [I]n which people who were previously eligible for Medicaid 'came out of the woodwork' and signed up for the program in 2014. ...
We’ve always known that there was some 'woodwork effect,' in which people who were already eligible signed up because of some combination of easier signup procedures and the heightened publicity that surrounded Obamacare’s passage and implementation. But these are huge numbers; the woodwork effect is more than twice as large as the number of people who became eligible for Medicaid thanks to Obamacare’s more generous criteria. This suggests the possibility that the plurality of people who gained insurance thanks to the law technically didn’t need a new program to become insured; all they needed to do was to sign up for public insurance they already qualified for.The underscoring is mine.
Certainly undercuts the "you can't repeal it" cries ... by about 44%.