The nation’s health insurers, resigned to the idea that Republicans will repeal the Affordable Care Act, on Tuesday publicly outlined for the first time what the industry wants to stay in the state marketplaces, which have provided millions of Americans with insurance under the law.

The insurers, some which have already started leaving the marketplaces because they are losing money, say they need a clear commitment from the Trump administration and congressional leaders that the government will continue offsetting some costs for low-income people. They also want to keep in place rules that encourage young and healthy people to sign up, which the insurers say are crucial to a stable market for individual buyers.

The demands are a sort of warning shot to Republicans. While the party is eager to repeal the law as quickly as possible, and many have promised a replacement, its members are sharply divided over what shape any new plan should take. If they do not come up with an alternative, more than 22 million people would be left uninsured, including the more than 10 million who have bought individual plans on state marketplaces.

On Tuesday, Marilyn Tavenner, the chief executive of America’s Health Insurance Plans, a leading industry trade group, warned that the state marketplaces were already on unstable financial footing. Failing to continue the funding aimed at low-income Americans, she said, would have far-reaching consequences because the business would become much tougher for insurers.