The U.S. House and U.S. Department of Health & HumanServices on Monday asked a federal appeals court to freeze foranother 90 days a dispute over billions of dollars in insurance industry subsidies under theAffordable Care Act, a delay that could furtherunnerve the health insurance markets.

The lawfulness of the subsidies — which the government pays to healthinsurers as part of a cost-sharing program to reduce premiums andother out-of-pocket expenses for low-income consumers — is thecenterpiece of a case in the U.S. Court of Appeals for theD.C. Circuit. An estimated 6 million consumers participate in thecost-sharing program.

The D.C. Circuit in December put the case on hold to allow theU.S. House of Representatives, which sued over the propriety of thesubsidies, and the incoming Trump administration to decide whetherand how to resolve the dispute. The court set a May 22 deadline forthe lawyers to advise the panel judges on the next steps in thelitigation.

“The parties continue to discuss measures that would obviate theneed for judicial determination of this appeal, including potentiallegislative action,” House general counsel Thomas Hungar wrote inthe filing, also signed by the Justice Department’s Alisa Klein, anappellate lawyer in the Civil Division.

U.S. House Republicans in 2014 sued health regulators to stopthe government from making those payments to insurers, arguing thatCongress never permitted them in the first place. A federal trialjudge, Rosemary Collyer, ruled for the U.S. House in May 2016. TheObama administration’s Justice Department, representing the U.S.Health and Human Services Department, filed the appeal.

Donald Trump’s win in November set up a tricky situation forRepublicans, who are now facing off in court against the JeffSessions-led Justice Department and HHS Secretary Tom Price. Asettlement wouldn’t automatically render void the reasoning behindCollyer’s injunction that blocked the cost-sharing program. FormerPresident Barack Obama’s Justice Department wanted the rulingoverturned on the ground the House didn’t have standing to sue inthe first place. That institutional concern could cut across partylines.

A group of insurance, medical and business associations —including America’s Health Insurance Plans, American MedicalAssociation and the U.S. Chamber of Commerce — on May 19 urgedCongress to fund cost-sharing reduction payments, known as CSRs.

"As providers of health care and coverage to hundreds ofmillions of Americans, we are writing again to you as leaders inCongress to express our serious concerns about the continueduncertainty around funding for cost-sharing reduction (CSR)payments," the groups wrote in their letter to U.S. Senate leaders."There now is clear evidence that this uncertainty is underminingthe individual insurance market for 2018 and stands to negativelyimpact millions of people."

More from their letter:

Unless CSRs are funded, a tremendous number of Americans willsimply go without coverage and move to the ranks of the uninsured.This threatens not just their own health and financial stability,but also the economic stability of their communities.

A spokesperson for America's Health Insurance Plans said onMonday: "We need swift, immediate action and long-term certainty onthis critical program. It is the single most destabilizing factorin the individual market, and millions of Americans could soon feelthe impact of fewer choices, higher costs, and reduced access tocare."

Sixteen state attorneys general last week urged the D.C. Circuitto let them intervene in the case to defend the subsidies. Thelawyers for the 15 states and the District of Columbia said theTrump administration can no longer be relied on to defend thecost-sharing subsidies. The state AGs on the brief includedCalifornia, New York, Pennsylvania, Connecticut and Illinois.

“In this litigation, the House of Representatives attacks acritical feature of the Patient Protection and Affordable Care Act— landmark federal legislation that has made affordable healthinsurance coverage available to nearly 20 million Americans, manyfor the first time,” the state AGs wrote in their filing, signed byCalifornia Solicitor General Edward DuMont. “If successful, thesuit could — to use the president’s expression — 'explode’ theentire act. Until recently, states and their residents could relyon the executive branch to respond to this attack. Now, events andstatements, including from the president himself, have made clearthat any such reliance is misplaced.”

The D.C. Circuit hasn’t yet ruled on whether to allow the statesto intervene in the dispute.

In Monday’s filing, lawyers for the House and the JusticeDepartment urged the appeals court to reject the interventionrequest. The D.C. Circuit in January turned down a request from twoindividual consumers, represented by Mayer Brown, to intervene inthe case.

Kristen Rasmussen in Atlanta contributed reporting.