Colorado HealthOP workers in Denver hand out literature and juice shots in this March 2014 photo.

 (AP Photo/Brennan Linsley)

Colorado's biggest nonprofit health insurer is closing, forcing 80,000 or so Coloradans to find a new insurer for 2016.

Colorado HealthOP announced Friday that the state Division of Insurance has de-certified it as an eligible insurance company. That's because the cooperative relied on federal support, and federal authorities announced last month they wouldn't be able to pay most of what they owed in a program designed to help health insurance co-ops get established.

The cooperative says that almost 40 percent of people who bought insurance through the state exchange are Colorado HealthOP members. They expect that closing their operations will cost taxpayers $40 million.

The Colorado announcement makes the co-op the fifth in the nation to collapse. Similar nonprofit insurers have already failed in Louisiana, Iowa/Nebraska, Nevada and New York.

Open enrollment for 2016 starts Nov. 1. The state Division of Insurance must first certify insurers before they're allowed to sell plans.