Conservative governors who shunned Medicaid expansion in their states are feeling vindicated in light of unexpectedly huge surges in Medicaid enrollment in neighboring states. But at the same time, as enrollment growth begins to level off, those who embraced it are touting the benefits.

More than 12 million people have signed up for Medicaid under the Affordable Care Act since January 2014. Many states that agreed to participate in the expansion, however, are now reeling from unexpected surges that already are straining their ability to pay for and provide services, Politico reports in a recent expose. Some states have had more than double the expected number sign up.

Meanwhile, one unanticipated consequence of the expansion (dubbed “the woodwork effect”) is a rise in enrollment of people who would have been eligible before the ACA but applied for benefits only after the momentum of the new law carried them to.

Some critics ponder how providers relying on Medicaid dollars, such as nursing homes, will fare down the road. The government has agreed to pick up the entire cost of the expansion through 2016. The commitment begins to decline by 10% the following year.

Supporters of the expansion praise the program because it provides needed coverage for woefully sick or disabled people who are too impoverished to obtain medical care otherwise. Moreover, some providers are receiving “billions of dollars from the federal government to cover low-income people, letting them save money on other programs that had been fully or partly funded through state dollars,” Politico added in its report.

Medicaid is the No. 1 payer of long-term care services in the United States.