HARTFORD (AP) — The state has started notifying thousands of Connecticut families that it might have to close a popular health insurance program for children if the U.S. Congress doesn't reauthorize federal funding.

The Department of Social Services began sending notices to parents and guardians last weekend, letting them know that funds for HUSKY B are expected to run out on Jan. 31 unless additional federal money becomes available. The letter urges parents and guardians to "act quickly" to enroll their children in new health coverage that will start on Feb. 1.

"After 20 years of offering health coverage to uninsured children in Connecticut through the CHIP (Children's Health Insurance Program) program, HUSKY B will end, as required by federal law. As a result, HUSKY B will not pay for services your child receives after Jan. 31, 2018," according to the letter, which notes coverage will continue if Congress votes to keep funding CHIP.

More than 17,000 low- and moderate-income children in the state could be affected if that funding is not approved, said Democratic U.S. Sen. Chris Murphy of Connecticut. He spoke Tuesday on the Senate floor, urging his Republican colleagues to reauthorize CHIP.

"We need to think about the crisis that many families are in today and will be in over the holiday season if we don't choose to do some basic things here," said Murphy, who also urged his colleagues to approve funding for community health centers.

DSS spokesman David Dearborn said the state has been using leftover federal funds to keep the program running since September 30, when Congress allowed the funding to expire.

In its letter to affected families, DSS said it plans to review their most recent application information on file and look for other possible health coverage options. For example, they may qualify for HUSKY A or an insurance plan through the state's health insurance marketplace, Access Health CT. To be eligible for HUSKY A, a family of four, for example, must earn annual income of less than $49,447.

There are two eligibility tiers under the HUSKY B program, which are facing possible closure. For the first tier, a family of four is eligible if they earn between $49,447 and $62,484. There is no monthly premium, but some copayments. Under the second level, a family of four is earning $62,485 to $79,458 and can receive coverage for a $30 monthly premium for the first child. Premiums are capped at $50, with some copayments.