Taking a harder line on health care, the Trump administration joined a coalition of Republican-led states Wednesday in asking a federal appeals court to entirely overturn former President Barack Obama’s signature health care law — a decision that could leave millions uninsured.

Congress rendered the Affordable Care Act completely unconstitutional in 2017 by eliminating an unpopular tax penalty for not having insurance, the administration and GOP states told the court.

The “Obamacare” opponents hope to persuade the 5th U.S. Circuit Court of Appeals in New Orleans to uphold U.S. District Court Judge Reed O’Connor’s ruling late last year striking down the law.

If the ruling is allowed to stand, more than 20 million Americans would be at risk of losing their health insurance, re-igniting a winning political issue for Democrats heading into the 2020 elections. President Donald Trump, who never produced a health insurance plan to replace “Obamacare,” is now promising one after the elections.

The Trump administration acknowledged it had changed positions in the case. Early on, the administration argued that only certain key parts of the ACA, such as protections for people with pre-existing medical conditions, should be invalidated. But it said other important provisions such as Medicaid expansion, subsidies for premiums and health insurance markets could continue to stand.

Wednesday, the administration said it had reconsidered in light of O’Connor’s ruling. “The remaining provisions of the ACA should not be allowed to remain in effect — again, even if the government might support some individual positions as a policy matter,” the administration wrote in its court filing.

The Justice Department’s legal brief also seemed to be trying to carve out some exceptions. For example, the administration said the ACA’s anti-fraud provisions should remain in effect.