In the midst of a pandemic and without an alternative health plan of its own, the Trump administration formally called on the U.S. Supreme Court to completely strike down the Affordable Care Act.
The administration makes the case in a legal brief filed late Thursday in the case brought by 20 Republican-led states that want to completely invalidate the law.
The justices will hear oral arguments as soon as October, which is just weeks before the general election.
Two lower federal courts have ruled that the ACA’s individual mandate is unconstitutional after the GOP Congress in 2017 zeroed out the penalty for going without health insurance. The Supreme Court had previously upheld the mandate on the grounds that it was a tax.
The lower courts also called into question the viability of the entire law without the mandate.
“The individual mandate cannot be severed from the remainder of the ACA,” writes Trump solicitor general Noel Francisco in his brief to the Supreme Court. “The entire ACA thus must fall with the individual mandate.”
California and 19 other Democrat-led states are defending the law.
"The ACA has been life-changing and now through this pandemic, we can all see the value in having greater access to quality healthcare at affordable prices," said California attorney general Xavier Becerra who is leading the defense. "Now is not the time to rip away our best tool to address very real and very deadly health disparities in our communities."
Nearly half a million Americans have signed up for health plans through the ACA so far in 2020, according to the Department of Health and Human Services -- a surge of enrollment, up 46% from this time last year, from workers who lost their jobs and employer-based insurance coverage in the coronavirus pandemic.
"We intend to win this," Becerra added.
President Trump in a June 2019 interview with ABC News promised to unveil a "phenomenal" new health care plan that he said would "be less expensive than Obamacare by a lot." He said the administration would be presenting a proposal “in about two months, maybe less," but no plan was ever announced.
"It’s very bad healthcare," Trump said of the ACA in May. "What we want to do is terminate it and give great healthcare."
Former Vice President Joe Biden defended Obamacare Thursday at campaign stop focused on health care, saying doing away with the ACA during a pandemic could be particularly harmful to many that need health care the most.
"I think it's cruel. It's heartless. It's callous. And it's all because, in my view, he can't abide the thought of letting stand on one of President Obama's greatest achievements, the Affordable Care Act," Biden said of the administrations' lawsuit.
Biden warned those who have survived COVID-19 and have subsequent health issues could be especially at-risk.
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.
Speaker of the House Nancy Pelosi issued a statement late Thursday night, calling the Trump administration's decision "unfathomably cruelty" to "rip away the protections and benefits of the Affordable Care Act in the middle of the coronavirus crisis."
"There is no legal justification and no moral excuse for the Trump Administration’s disastrous efforts to take away Americans’ health care," she said.
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.
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, but could be at risk.
The case marks the third time the justices will consider 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.
ABC News' Molly Nagel and William Mansell contributed to this report.