Donald Trump has lost the presidential election , but his last, desperate effort to kill the Affordable Care Act will get its day before the U.S. Supreme Court on Tuesday, when the justices hear arguments in a Republican-backed lawsuit alleging that Obamacare is unconstitutional.

The case, known as California v. Texas , is the third such challenge to reach the high court since the laws 2010 enactment. And the stakes are as high as ever. If the justices wipe out the Affordable Care Act, as 18 Republican state officials and the Trump administration have asked it to do, roughly 21 million Americans could lose health insurance, according to independent projections.

The laws protections for people with preexisting conditions would no longer be in effect, less-visible reforms covering everything from billing fraud to food calorie postings would vanish, and the entire health care system could plunge into chaos .