Nationwide, about 11.5 million uninsured people fall into that category, the Urban Institute said. Roughly 1.8 million live in the seven states that have said they won't take part in the Medicaid expansion.
Some of those people might be eligible for Medicaid already, but aren't enrolled. And not all 11.5 million will have to go without coverage, because several states -- 12 so far -- plan to implement the new expansion anyway.
The federal government will initially cover the entire cost of the expansion, dropping to 90 percent after the first few years.
States challenged the policy as coercive, saying they shouldn't have to sacrifice their entire Medicaid programs just because they don't want to expand the program further.