HARTFORD, Conn. — The two remaining insurers offering health care plans to consumers could decide this fall to leave Connecticut’s health insurance exchange, while uncertainty over billions of dollars in federal payments is exacerbating the problem, the CEO of Access Health CT warned on Wednesday.

“This is a threat knocking on our doors for the next open enrollment,” Jim Wadleigh told members of Access Health CT’s board of directors.

Open enrollment for 2018 coverage begins Nov. 1. Meanwhile, the state’s two remaining carriers on the exchange, Anthem and ConnectiCare, have until Sept. 8 to notify Access Health CT about whether they’ll continue to participate in the individual market. Wadleigh stressed that coverage for current Access Health CT customers will remain unchanged through December, no matter what happens in Washington.

There are currently about 98,000 customers on the exchange. About 42,000 qualify for the federally funded “cost-sharing” subsidies for copays and deductibles under the Affordable Care Act.

Wadleigh said he and the state’s remaining insurers are closely watching whether President Donald Trump will move ahead with a threat to push “Obamacare” into collapse. He recently tweeted how “BAILOUTS for Insurance Companies … will end very soon!”, referring to the funding for the subsidies But a federal appeals panel in Washington late Tuesday said a group of states, including Connecticut, can defend the legality of the government subsidies if the Trump administration decides to stop paying the money.

Meanwhile, there’s a bipartisan group of federal lawmakers that’s working to provide at least a temporary guarantee for the subsidies before the open enrollment season begins.

Wadleigh said a permanent agreement to pay insurers the subsidies is among the several things needed to stabilize the system and help persuade insurers to continue offering policies through the exchanges.

“Right now, on a daily basis, we see a number of tweets that are coming out of Washington, D.C. that talk about the potential of not making those cost sharing reduction payments,” Wadleigh said. “That adds risk to an industry that is solely based on avoiding risk.”

The uncertainty comes as Connecticut grapples with its own budget deficit problems. Ben Barnes, an Access Health CT board member and the state’s budget director, said while the administration is concerned citizens could ultimately lose coverage, the state is not in the financial position to cover the cost of the subsidies to insurers.

“That would be an additional expense that would be difficult for the state to assume right now,” he said.

If the federal payments aren’t approved, insurance premiums could climb by roughly 20 percent. The state’s Department of Insurance is currently reviewing rate increase requests from Anthem and ConnectiCare. Commissioner Katharine Wade said she hopes the federal payment issue is settled over the next couple of weeks. Her agency plans to release its decision by the end of August, giving the carriers time to make an informed decision about whether to remain in the Connecticut exchange.

Wadleigh has been warning for months that steps need to be taken to help the two insurers on the exchange remain financially sustainable in Connecticut. At its height, the state had four insurers offering individual plans in 2015. He said the individual market has had its own challenges, regardless of the subsidies issue.

Last month, the Access Health CT board discussed the possibility of not having any insurers for 2018. Officials said they planned to develop a strategy for transitioning customers from the exchange, the only place where subsidies to consumers is available, to the individual marketplace. But Wadleigh said he still hopes that won’t be necessary.

“It could come to a point where we may not have carriers,” Wadleigh said. “But I think there’s going to be some more executive-level conservations that will help to see how we get through, out the other side.”