Protections for preexisting conditions and insurance subsidies are on the line.

The Supreme Court announced Monday that it will decide the fate of the Affordable Care Act in its next term, setting the stage for a blockbuster ruling on health care for millions of Americans just after the 2020 election.

The justices granted the appeal from California and 19 other Democrat-led states seeking to uphold the health care law in a simple order without explanation. Oral arguments will be scheduled after October with a decision likely several months later.

“As Texas and the Trump Administration fight to disrupt our healthcare system and the coverage that millions of people rely upon, we look forward to making our case in defense of the ACA. American lives depend upon it,” said California Attorney General Xavier Becerra who leads the coalition defending the law.

At the heart of the case is whether the law’s individual insurance mandate — which was initially upheld by the Court under Congress’ power to tax — remains constitutional after Republican lawmakers zeroed out the financial penalty for being uninsured in 2017.

Late last year, a federal appeals court struck down the mandate and called into question whether the rest of the health law could still stand without it.

“The individual mandate is unconstitutional because it can no longer be read as a tax, and there is no other constitutional provision that justifies this exercise of congressional power,” reads the majority opinion from the Fifth Circuit U.S. Court of Appeals.

The Trump administration has asked the courts to invalidate the entire law but has not yet put forward a viable alternative.

Industry groups and independent health care analysts say abruptly wiping out Obamacare would mean a highly disruptive shift in the health care of millions of Americans.

The ACA has sharply reduced the number of uninsured Americans since 2010, covering 20 million more people than if the law had not taken effect, according to the nonpartisan Kaiser Family Foundation.

An estimated 52 million Americans have preexisting health conditions that insurers could have denied coverage to under pre-ACA rules in most states, the foundation said.

Preexisting condition protections and Obamacare insurance subsidies remain in place, for now, as the case continues. Most consumers will not experience any immediate change in benefits, experts say.

The case will mark the third time the justices have considered the constitutionality of the Affordable Care Act since it was signed by President Barack Obama in 2010. Chief Justice John Roberts in 2012 famously cast the decisive vote, siding with the court’s liberal justices to uphold the law.

Public polling has shown growing support for Obamacare and that voters consider health care a top issue headed into the 2020 presidential election.