Maine voted overwhelmingly on Tuesday to become the first state in the nation to expand Medicaid by ballot initiative, approving the measure by a nearly 20-point margin. But Republican Gov. Paul LePage, a vehement opponent of Medicaid who has vetoed expansion bills five times since the Affordable Care Act became law, is threatening once again to block more than 80,000 low-income Mainers from gaining access to government health insurance.

In a statement Wednesday morning, LePage said he would not allow expansion to go into effect until the program “has been fully funded by the Legislature at the levels DHHS has calculated.”

But Mainers for Health Care, the organization behind the campaign to expand Medicaid, said despite LePage’s bluster, he can’t stop the expansion train without violating state law.

“Under the state constitution, 45 days after the legislature reconvenes, Medicaid expansion will become the law of the state,” the group’s spokesman David Farmer told TPM. “According to the statute, the Department of Health and Human Services has 90 days after that to submit an implementation plan to the federal government, and the implementation itself will take place in mid-August of 2018.”

“If the governor isn’t willing to follow the law,” he added, “we will take it to the courts if necessary.”

Under the Affordable Care Act, the federal government pays the vast majority of the cost for states that choose to expand Medicaid, but states have to come up with 10 percent of the necessary funding by 2020.

Maine’s non-partisan Office of Fiscal and Program Review calculated that the state will need to spend nearly $55 million more per year to expand Medicaid, but will draw an additional $525 million from the federal government.

LePage, however, has cited wildly different cost estimates, relying mainly on numbers from the conservative Maine Heritage Policy Center that clock in around $100 million per year.

“This fiscally irresponsible Medicaid expansion will be ruinous to Maine’s budget,” LePage warned in Wednesday’s defiant statement.