A federal judge in Fort Worth handed down a ruling late Friday evening that declared the Affordable Care Act unconstitutional, threatening the longevity of what was arguably the crowning achievement of Barack Obama’s presidency.

While the ruling is an undeniable victory for Attorney General Ken Paxton and the State of Texas, which led a coalition of twenty states in a February lawsuit challenging the Affordable Care Act, its long-term impact is less clear. According to the New York Times, the case will “almost certainly” wind up in the U.S. Supreme Court’s hands, meaning there’s a long way to go before the ruling may ultimately go into effect, though legal experts have already cast significant doubt on whether the ruling will hold up. In the meantime, the White House told Bloomberg News that the Affordable Care Act remains in effect pending an appeal, and the ruling does not currently affect 2019 coverage plans.

Still, Paxton and his supporters were very happy after news of the ruling broke—note the three exclamation points in Paxton’s tweet!

“Today’s ruling halts an unconstitutional exertion of federal power over the American healthcare system,” Paxton said in a more subdued news release. “Our lawsuit seeks to effectively repeal Obamacare, which will give President Trump and Congress the opportunity to replace the failed social experiment with a plan that ensures Texans and all Americans will again have greater choice about what health coverage they need and who will be their doctor.”

In a separate press release, the conservative Texas Public Policy Foundation called the ruling a “historic win,” but noted that the judge’s decision is “only the first step” in dismantling the Affordable Care Act. “We need to focus on the future and look to states like Texas to lead in restoring the relationship between doctor and patient, unencumbered by government and insurance company red tape,” Robert Henneke, an attorney representing the plaintiffs and director at the Texas Public Policy Foundation, said in the press release. “Let’s focus on solutions that will drive down costs and restore choice in doctor.”

In his ruling, U.S. District Judge Reed O’Connor claimed that the Affordable Care Act’s individual mandate was unconstitutional, thus rendering the entire act unconstitutional. Previous court rulings have upheld the Affordable Care Act against similar challenges, including a narrow 2012 U.S. Supreme Court decision that declared the individual mandate constitutionally safe because it falls under Congress’s legal power to levy taxes.

But Paxton and his cohort of states argued in their lawsuit that when the GOP’s 2017 tax bill repealed the tax penalty for those who do not comply with the individual mandate, it rendered moot the Supreme Court’s 2012 rationale for upholding the Affordable Care Act. O’Connor agreed, writing that the individual mandate provision is the “keystone” of the Affordable Care Act and is “inseverable” from the rest of the act, and that in declaring the provision unconstitutional, the rest of the act is unconstitutional as well. In short, since there’s no tax penalty for the individual mandate anymore, it’s no longer considered a “tax,” and is not covered under Congress’s constitutional power to tax.

O’Connor has a reputation for issuing conservative-friendly rulings in cases that challenge policies that are popular among Democrats. The New York Times profiled O’Connor the day after the Affordable Care Act ruling, citing him as a prime example of federal district courts becoming increasingly “politically weaponized,” noting that the George W. Bush appointee “has been at the center of some of the most contentious and partisan cases involving federal power and states’ rights, and has sided with conservative leaders in previous challenges to the health law and against efforts to expand transgender rights.”

There is, of course, intense opposition to O’Connor’s latest ruling among Democrats and health care professionals.

“Today’s ruling is an assault on 133 million Americans with preexisting conditions, on the 20 million Americans who rely on the ACA’s consumer protections for healthcare, on America’s faithful progress toward affordable healthcare for all Americans,” California attorney general Xavier Becerra said in a statement, according to the Texas Tribune (California led a coalition of states that intervened in the lawsuit in defense of the Affordable Care Act). “The ACA has already survived more than 70 unsuccessful repeal attempts and withstood scrutiny in the Supreme Court. Today’s misguided ruling will not deter us: our coalition will continue to fight in court for the health and wellbeing of all Americans.” House and Senate Minority Leaders Nancy Pelosi and Chuck Schumer both commented on Twitter:

“Today’s decision is an unfortunate step backward for our health system that is contrary to overwhelming public sentiment to preserve pre-existing condition protections and other policies that have extended health insurance coverage to millions of Americans,” said Dr. Barbara L. McAneny, president of the American Medical Association, which filed an amicus brief urging O’Connor to reject Paxton’s lawsuit. “It will destabilize health insurance coverage by rolling back federal policy to 2009. No one wants to go back to the days of 20 percent of the population uninsured and fewer patient protections, but this decision will move us in that direction.”

As the Washington Post notes, the ruling actually puts Republicans in a tricky spot politically, as they now must weigh the legal victory against a growing concern among voters that the GOP’s efforts to dismantle the Affordable Healthcare Act would put about 20 million Americans at risk of losing health care coverage, a sentiment the Democrats were able to use to their advantage while campaigning for the midterm elections. Even the conservative editorial board of the Wall Street Journal felt the ruling was short-sighted, writing on Saturday that “the risk is that the lawsuit will cause Republicans in Congress to panic politically and strike a deal with Democrats that reinforces ObamaCare.”

Judge O’Connor drew harsh bipartisan criticism for the logic of his decision as much as for its timing. The ruling was handed down late Friday evening, after most courts were already closed for the weekend and on the eve of the deadline for the Affordable Care Act’s open enrollment period for 2019 coverage. According to the Post, after the federal government decided not to intervene in the lawsuit on the side of the Affordable Care Act, Department of Justice attorneys had asked Judge O’Connor not to issue any injunction until the open enrollment period ended. “The last thing we want is for there to be chaos in the insurance markets and for people who currently have health care to lose that health care,” Deputy Assistant Attorney General Brett Shumate told the judge in September, according to the Post. Instead, the timing of O’Connor’s ruling added confusion to an already stressful deadline period.

It’s unclear what would replace the Affordable Care Act if it is ultimately struck down. On Monday, Governor Greg Abbott told the Dallas Morning News that he plans to work with the Trump administration to pursue a short-term plan of action while Texas lawmakers and regulators work to put together a state health care plan, but he offered no concrete details of what that new plan would actually look like. “As the ACA lawsuit goes through the appellate process, Texas will work with the Administration to get appropriate waivers from federal law allowing insurers to provide coverage at lower rates while ensuring that Texans with pre-existing conditions continue to have access to quality healthcare,” Abbott said in the statement. “Additionally, Texas will begin the process of reforming state regulations and proposing changes to laws that will achieve those same goals. Importantly, Texas will strive to expand healthcare insurance coverage, reduce the cost of healthcare, and ensure that Texans with pre-existing conditions are protected.”