The Supreme Court almost certainly won’t take up a Republican lawsuit to eliminate the Affordable Care Act before the presidential election this year, justices announced Tuesday.

The majority-Democrat House of Representatives and Democratic state attorneys general, who are defending the law against a group of Republican state officials and President Donald Trump’s Justice Department, asked the high court to expedite the case, known as Texas v. United States. On Tuesday, the Supreme Court said it would not take up the case in its next session, all but erasing the possibility of an election-season ruling that would cause an estimated 20 million people to lose their health coverage.

Whenever a ruling does come, it has the potential to invalidate the Affordable Care Act and wreak havoc on the U.S. health care system.

The Urban Institute projects that 20 million people would lose health coverage under such a decision, which would end the law’s Medicaid expansion to poor adults and its subsidies on private health insurance for low- and middle-income families.

Because the GOP plaintiffs have sought to have the entire law overturned, the consequences would reach far beyond those who would find themselves immediately uninsured.

The Affordable Care Act’s guarantee that people with preexisting conditions can get coverage would go away. Rules requiring insurance companies to cover the “essential health benefits” defined by the law, including prescription drugs, hospital care and preventive medicine, would disappear. Without the Affordable Care Act, insurers also could resume setting dollar limits on annual and lifetime medical care for each policyholder. Medicare beneficiaries would pay more for prescriptions because they would lose additional assistance provided by Obamacare.

Texas Attorney General Ken Paxton and a group of other state Republican officials filed their lawsuit in February 2018, and U.S. District Judge Reed O’Connor in Fort Worth, Texas, ruled in their favor in December 2018.

A federal appeals court in New Orleans partly upheld that decision last month and sent the case back to O’Connor for further consideration. The law remains in place while the case continues to work its way through the courts. Given the stakes, it’s likely that the Supreme Court ultimately will have to make a final decision on the lawsuit.

The plaintiffs’ argument draws on two significant developments from the nearly decade-long history of the Affordable Care Act.

The state GOP officials brought the lawsuit shortly after Congress in 2017 eliminated the fines associated with the Affordable Care Act’s “individual mandate” that most U.S. residents have health coverage or pay tax penalties. Citing a 2012 Supreme Court ruling that the mandate was a constitutional exercise in Congress’ right to levy taxes, the plaintiffs contend that the lack of fines ― that is, taxes ― renders the mandate itself unconstitutional. Furthermore, the Republicans cite the Justice Department’s claims under then-President Barack Obama that the mandate is so essential to the law’s functioning that the entire statute must be struck down if the mandate were.

Trump’s Justice Department declined to defend the Affordable Care Act in court, a break with standard practice when federal laws are subject to legal challenges. Moreover, the Trump administration actually joined with its state counterparts in seeking to invalidate the law in June 2018. At first, the administration only sought to have the courts undo the Affordable Care Act’s protections for people with preexisting conditions and some related provisions, but later it signed on to the state officials’ goal of eliminating the whole statute.

Immediately prior to the federal government abandoning its defense of the law, a trio of Justice Department lawyers removed their names from the government’s brief, and Joel McElvain, a 20-year veteran of the department, quit in protest. Trump nominated the lead lawyer who remained, Chad Readler, for a federal judgeship the same day the department submitted its brief; the Senate confirmed him last March.

Legal scholars from the left and right have derided the plaintiffs’ legal arguments, but one federal circuit court judge and two appeals court jurists were unmoved by those criticisms so far. These Republican-appointed judges also were unpersuaded by the Democratic defense of the law, including the assertion that Congress clearly didn’t intend to repeal the entire law when it eliminated the mandate fines in 2017, as evidenced by the fact that Congress did not, in fact, vote to repeal the entire law.

The plaintiffs in Texas v. U.S. are the GOP officials from Alabama, Arizona, Arkansas, Florida, Georgia, Indiana, Kansas, Louisiana, Mississippi, Missouri, Nebraska, North Dakota, South Carolina, South Dakota, Texas, Utah and West Virginia.

California Attorney General Xavier Becerra is leading the defense along with his counterparts from Colorado, Connecticut, Delaware, Hawaii, Illinois, Iowa, Kentucky, Massachusetts, Michigan, Minnesota, Nevada, New Jersey, New York, North Carolina, Oregon, Rhode Island, Vermont, Washington state and the District of Columbia. The Democratic-led House of Representatives joined the defense last February.