DENVER — Thousands of healthcare workers are threatening to walk off the job as a potential strike looms at Kaiser Permanente.

If it happens it would be the largest healthcare strike in Colorado history.

The Service Employees International Union Local 105 represents more than 3500 Kaiser workers in Colorado. The union says 96 percent of its voting members supported authorizing a strike.

Kaiser is the largest private health insurer in Colorado. About one fourth of all Coloradoans covered under workplace plans receive their care through Kaiser Permanente.

Union members say the largest sticking point in negotiations is annual cost of living increases. The union wants a 3% raise, while Kaiser is offering just 1% this year to its workers in Colorado. Colorado employees would receive wage increases of 2% after 2019, every year from 2020 through 2022.

Kaiser has offered a 3% raise per year over the next 4 years to workers in California.

“We’re wanting fair wages across the board. We’re wanting equity in the region of Colorado just like California and other regions,” said Sadé Kiel, a member of the Kaiser customer contact center in Denver.

The union also says it opposes a two tier system being proposed by Kaiser where new hires would receive lower starting play and would not qualify for the pension plan and reduced medical benefits during retirement. Kaiser Permanente disputes the unions claims about that system and says the union has made several false claims.

Many patients are worried how a potential strike could impact them.

Gloria Stroh has kidney problems is a stage three diabetic. The 63 year-old is also semi-retired and on a fixed income. She is worried a strike would impact her medical care and her insurance.

“I’m really scared if they raise salaries they’re going to raise our copay. That’s my only opinion,” she said.

Sadé Kiel says Gloria’s fears aren’t unfounded. She says thousands of temp workers would have to fill in during a strike. The union believes some smaller Kaiser Permanente facilities in Colorado would possibly be temporarily shut down and the union is warning of incredibly long wait time to fill prescriptions and receive test lab results.

“It’s definitely a ripple effect. Care is definitely going to be impacted because no one knows how to take sure of the patients like we do,” said Kiel.

Kaiser Permanente wouldn’t discuss specific plans on how to fill the positions left vacant during a strike, but did tell FOX3, “We will continue to care for our members in the event of a strike and have strong plans in place. We have 1,200 physicians and thousands of additional staff in Colorado.”

Kaiser also says, “It is important to understand that a strike vote does not mean that a strike is imminent, although it does place Kaiser Permanente in the position of having to spend millions of dollars preparing for the threat of a strike event. Our first priority is always continuity of care for our patients and members.”

However, patients like Gloria Stroh are wondering what exactly that means for their care and their health insurance.

“That’s why I’m so scared. I feel depressed,” she said.

Both sides will return to the negotiating table on Monday. An actual strike wouldn’t occur until sometime in  October, and by law the union has to give a ten day notice of a strike to warn patients.

Union members will be attending a strike summit on Saturday in Denver to prepare for a strike.