PORTLAND, Maine (AP) — The U.S. Supreme Court declined Tuesday to hear an emergency appeal of a vaccine requirement imposed on Maine health care workers, the latest defeat for opponents of vaccine mandates.

It was the first time the Supreme Court weighed in on a statewide vaccine mandate. It previously rejected challenges of vaccine requirements for New York City teachers and Indiana University staff and students.

Justice Stephen Breyer rejected the emergency appeal but left the door open to try again as the clock ticks on Maine’s mandate. The state will begin enforcing it Oct. 29.

The Maine vaccine requirement that was put in place by Democratic Gov. Janet Mills requires hospital workers and nursing home workers to get vaccinated or risk losing their jobs.

Opponents tried to block the mandate, but a federal judge rejected the request on Oct. 20. The judge said the record indicated regular testing alone wasn’t sufficient to stop the spread of the delta variant.

A three-judge panel of the 1st U.S. Circuit Court of Appeals let the ruling stand in a one-sentence statement two days later.

The Liberty Counsel, which filed the lawsuit in federal court in Maine in August, claimed to be representing more than 2,000 health care workers who don’t want to be forced to be vaccinated.

Dozens of health care workers have opted to quit, and Central Maine Medical Center in Lewiston already curtailed some admissions because of an “acute shortage” of nurses.

But most health workers largely have complied with the requirement.

State agencies vowed to work with individual hospitals and nursing homes to address individual workforce issues.