The Trump administration and 18 Republican-leaning states argue the whole law must go. After federal lawmakers in 2017 zeroed out the individual mandate’s penalty for lacking health insurance, the entire Affordable Care Act (ACA) must fall with it, they contend.

There’s no reason the whole law has to collapse and deprive an estimated 20 million people of health insurance, say more than 20 Democrat-leaning states and the Democrat-controlled House of Representatives.

Now it’s a question of which side can convince at least five members of the high court that they have the better arguments, an issue that has new resonance as the coronavirus pandemic continues to surge. More than 10.1 million Americans had contracted COVID-19 as of Tuesday, according to a running tally from Johns Hopkins University.

The Supreme Court case, Texas v. California, is about health care. But it’s also about math.

There’s the addition of Justice Amy Coney Barrett, a conservative-leaning judge who replaces Justice Ruth Bader Ginsburg, a member of the court’s liberal wing who died in September at age 87.

Then there’s the addition of President-Elect Joe Biden, a proponent of the health-care law who is poised to take office in January as the court mulls its decision, which is expected for release in spring 2021.

See also: Supreme Court increasingly likely to uphold Obamacare even after Barrett’s confirmation, analysts say

Biden, who was vice president when President Barack Obama enacted the law in 2010, can’t stop the court from deciding the case once he takes office, legal observers say. But with court permission, his administration can pivot and argue the law should be upheld.

Biden was scheduled to speak later Tuesday on the lawsuit, according to his transition team.

The court’s ruling could determine health insurance access for millions during a pandemic

The Supreme Court’s ruling on the Affordable Care Act would have fairly immediate ramifications for many Americans who have lost their employer-sponsored insurance amid layoffs triggered by the coronavirus pandemic.

A recent report from the Economic Policy Institute, a nonprofit, non-partisan think tank, estimated that around 6.2 million workers lost access to health insurance they got through their employers as a result of being let go since the onset of the coronavirus pandemic. That figure takes into account workers who were originally laid off but have since found new employment.

In many cases, these workers’ health-care plans also covered their spouses, partners and dependents. Altogether, the rise in unemployment has cost some 12 million people their health-insurance coverage.

Because of the expansion of health-insurance options created by the Affordable Care Act, though, most of these workers are eligible for government-subsidized health insurance.

Open enrollment for health care through the Affordable Care Act’s marketplace runs through Dec. 15.

A separate study from the Kaiser Family Foundation found that nearly half of people who became uninsured after job loss were eligible for Medicaid. And roughly a quarter of those people who lost their employer-sponsored plans could qualify for subsidized insurance purchased through the insurance marketplaces set up by Obamacare.

“Some people will fall outside the reach of the ACA, particularly in January 2021 when [unemployment insurance] benefits cease for many and some adults fall into the Medicaid coverage gap due to state decisions not to expand coverage under the ACA,” the researchers wrote.

All told, millions of Americans had health insurance coverage that was made possible by Obamacare before the coronavirus pandemic began. Around 11.4 million people across the country enrolled in health-insurance plans through the insurance exchanges, according to data from the Centers for Medicare and Medicaid Services.

And as of January 2020, 70.7 million individuals were enrolled in Medicaid or the Children’s Health Insurance Program (CHIP), up from 14.2 million in 2013.

Another factor in Obamacare’s expanded coverage that’s also of significant concern for many Americans in the COVID era: The requirement for insurers to provide coverage to people with pre-existing conditions.

That’s because COVID-19 could be considered a pre-existing condition, especially for individuals with lingering symptoms.

Prior to the passage of Obamacare, health insurers could deny coverage, limit payouts or charge higher premiums to people with pre-existing medical conditions. If the Supreme Court were to eliminate the Affordable Care Act, those protections would likely go away.

That substraction could bring some more costly additions, some researchers say. The pandemic may have already added on approximately 3.4 million adults under age 65 who caught COVID-19 to the ranks of Americans with a pre-existing condition, according to the Commonwealth Fund, a private foundation offering grants and analysis on health care matters.

Before the pandemic’s onset, America had up to 133 million people with one or more pre-existing condition, Commonwealth Fund researchers said.

(On the campaign trail, Trump and Vice President Mike Pence said pre-existing conditions would be protected, but critics have said the GOP plans and protections were short on details.)

How will Justice Barrett affect the case decision?

Democrats have warned that Barrett’s nomination to the court could mean the end of the Affordable Care Act. Barrett has written in the past criticizing Chief Justice John Robert’s decision in the 2012 case, even going so far as to say that the legislation should be called “SCOTUScare.”

But Republican lawmakers said Barrett’s position on the case is unknown. And Barrett said during her confirmation hearings that she made no promises to anyone in exchange for her nomination.

“I have not made any commitments or deals or anything like that,” she said at the hearings. “I am not here on a mission to destroy the Affordable Care Act. I’m just here to apply the law and adhere to the rule of law.”

This story was updated on November 10, 2020.