The gravest danger facing Obamacare now is not legislative action — it’s executive inaction. Fortunately for the millions who rely on the Affordable Care Act, the states can save the health care law from “exploding.” But they need to move fast.

President Donald Trump’s latest bid to repeal the ACA looks as though it’s destined to meet the same fate as House Speaker Paul Ryan’s failed effort last month. Still, Trump has the ability — and quite likely the inclination — to undermine the health care law by deliberately failing to carry out important elements of it.

Obamacare faces four near-term threats from the president. First, the Trump administration could stop enforcing the individual mandate, which requires most individuals to have health insurance or else pay a penalty to the IRS. Trump can’t change the law without an act of Congress, but he might be able, through directives from the Oval Office, to stop the IRS from collecting the penalty.

The IRS has already said that for this tax season it will process so-called silent returns — returns filed by taxpayers who don’t indicate whether they had health coverage throughout the prior tax year. In other words, you can now go without health coverage, not pay a penalty, and still claim a tax refund when you file. (Under law, you still owe a penalty for failing to obtain insurance, but whether the IRS will ever come after you for the money is anyone’s guess.)

If young, healthy adults drop coverage because they don’t expect to pay a penalty, then the people in the risk pools on the exchanges will become older and sicker, on average, leading insurers to raise premiums for everyone. And if the healthy adults who drop coverage turn out not to be as healthy as they thought, then they will show up in emergency rooms without insurance. Hospitals will then have to provide them with uncompensated care, imposing costs borne by the rest of society.

The ACA is threatened by different kinds of malign neglect

A second and related threat is that the Trump administration will stop enforcing the employer mandate. Under the employer mandate, a firm with 50 or more full-time employees that fails to provide health insurance for its workforce faces a penalty of up to $2,260 per employee per year.

Trump signed an executive order on his first day in office telling his secretary of Health and Human Services, as well as other administration officials, to “waive, defer, grant exemptions from, or delay the implementation of” virtually all Obamacare provisions. We will soon see whether that leads HHS to carve out new exceptions to the employer mandate, in which case we can expect some firms to drop coverage and add their workers to the ranks of the uninsured.

A third threat is that the Trump administration will halt efforts to encourage people to buy insurance. Days before the January 31 enrollment deadline for 2017 coverage, the Trump administration pulled advertisements reminding consumers to sign up. We can expect the Trump administration to make even less of an effort to encourage sign-ups for 2018. Not only will that increase the ranks of the uninsured — a bad thing in itself — but the fewer consumers who buy coverage on the exchanges, the less likely it is that insurers will want to stay in the game.

A fourth threat, and probably the most pressing, is that the Trump administration will stop reimbursing insurers for costs the law requires them to take on. Under the Affordable Care Act, insurers must cover a portion of the costs that low-income households enrolled in individual-market plans would otherwise pay out of pocket; those “cost-sharing reductions” are then reimbursed by HHS.

So far, the Republican-controlled Congress has refused to appropriate funds for the reimbursements owed to insurers. The Obama administration paid the reimbursements anyway, but the House of Representatives responded by suing to stop those payments from continuing. That litigation continues, and while HHS is still making the payments for the time being, it’s not clear how much longer that will last.

What if HHS stops paying? A provision of the ACA requires insurers to make the cost-sharing reductions regardless of whether they are reimbursed by HHS. What’s more, the law also requires HHS to reimburse the insurers regardless of whether Congress appropriates funds. So if Congress doesn’t provide the money, then the insurers can sue the federal government in the Court of Federal Claims. The law is on the insurers’ side, and once the insurers have a court verdict in their favor, the reimbursements can be paid out of the federal government’s Judgment Fund.

But that process could take years, and it seems unlikely that insurers will be willing to shoulder more than $7 billion in annual costs while waiting for federal reimbursement. Many insurers may decide to pull out of the exchanges instead.

States don’t have to rely on Washington to enforce the individual or employer mandates

All this might make it sound like Obamacare is headed for a death spiral. It is not — at least, not yet. But it may be in need of some emergency treatment. And while Congress won’t come to the rescue, the states can.

First, the states can pick up the slack where the individual mandate is concerned. States should pass their own provisions that operate as fail-safes for the federal law. They should require individuals without insurance to pay the penalty to the state (allowing, of course, a full credit for amounts paid to the federal government). Anyone who complies with the federal mandate by obtaining insurance or paying the penalty to the IRS wouldn’t owe anything to the states, but people who ignore the federal law thinking that the IRS won’t come after them will face state tax collectors instead.

Second, states should pass similar fail-safes for the employer mandate. If the Trump administration tries to open up loopholes that allow employers to dump their employees onto the exchanges, then the states can close those loopholes on their own. They can require any firm with 50 or more full-time employees that doesn’t provide coverage and doesn’t pay the federal penalty to make that payment to the state instead.

Third, states should use the revenues they raise from the backup individual and employer mandates to fund their own enrollment campaigns — paying for advertising and in-person outreach. They could kick in additional funding as well, which would be a wise investment in the long run. Getting more of their residents insured through the exchanges will mean that more federal premium tax credit dollars will flow into the states. And with more individuals insured, the states will bear less of a burden for uncompensated care.

Fourth, if Trump stops paying reimbursements, the states should promise to reimburse insurers for making cost-sharing reductions until the federal government ultimately pays up. (This guarantee should come with full “subrogation” rights — meaning that if a state reimburses an insurer today and the federal government finally pays two years from now, the federal payment goes to the state, not the insurer.)

Yes, the states will bear a short-term cost while the issue is being litigated, but ultimately the courts will order the federal government to pay and the states’ treasuries will be replenished. In the meantime, the state guarantee will encourage insurers to remain on the exchanges rather than running for the exits.

These four steps — a backup individual mandate, a backup employer mandate, investments in state-level enrollment campaigns, and state guarantees for insurer reimbursements — will make it much more likely that Obamacare survives intact.

But the states will need to take these steps soon. June 21 is one important deadline for insurers to decide whether they will participate in the Healthcare.gov exchanges for 2018. Some states that run their own exchanges have earlier deadlines; California’s is May 1. By acting quickly, states can bolster insurance companies’ confidence that the marketplaces will remain functional regardless of what steps the Trump administration takes to undermine Obamacare.

Far from a “federal takeover” of health care, Obamacare actually gives the states considerable power to shape policy. They should use that power to preserve the health care law from a president bent on destroying it — and to protect the millions of Americans who depend on it.

Tom Baker is the William Maul Measey professor of law and health sciences at the University of Pennsylvania Law School and director of the Health Insurance Exchange Research Group at Penn’s Leonard Davis Institute for Health Economics. Daniel Hemel (@danieljhemel) is an assistant professor at the University of Chicago Law School.

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