Critics are slamming Amazon-owned Whole Foods over its plan to cut medical benefits for hundreds of part-time workers next year.

The benefit cuts will affect part-time Whole Foods employees who work at least 20 hours a week, Business Insider reported on Thursday.

Rep. Alexandria Ocasio-Cortez weighed in on the move on Saturday, calling it "part of the casual dehumanization of working people."

"Your ability to get insulin or see a doctor shouldn't depend on how generous a billionaire is feeling today," Ocasio-Cortez tweeted Saturday in a likely reference to Jeff Bezos, the billionaire CEO of Amazon. "Employers stripping healthcare, either by taking it away or worsening it, is just part of the casual dehumanization of working people to increase returns for the rich."

Sens. Bernie Sanders and Elizabeth Warren used the decision as an opportunity to advertise their Medicare-for-all proposals for healthcare reform.

"Your ability to get health care should not be dependent on the whims of your employer," Sanders tweeted on Friday. "It should be guaranteed under Medicare for All."

Warren chimed in on Saturday, tweeting, "Jeff Bezos committed to providing his employees 'important benefits' — right before Whole Foods cut health care benefits for hundreds of employees. This is exactly why we need #MedicareForAll."

Warren's tweet was referencing a statement that Bezos signed in August along with executives from 180 other companies that promised to invest in employees, starting with "compensating them fairly and providing important benefits."

Read more: Whole Foods is cutting medical benefits for hundreds of part-time workers

The changes to medical benefits will take effect on January 1 and affect just under 2% of Whole Foods' total workforce, a company spokesperson told Business Insider last week.

Whole Foods said it was making the change "to better meet the needs of our business and create a more equitable and efficient scheduling model."

"We are providing team members with resources to find alternative healthcare coverage options, or to explore full-time, healthcare-eligible positions starting at 30 hours per week," the spokesperson said. "All Whole Foods Market team members continue to receive employment benefits including a 20% in-store discount."

The United Food and Commercial Workers International Union, which is one of the largest unions in the US, called the move a "brazen" attack against workers.

"Amazon's plan to cut healthcare for these part-time employees is one of Jeff Bezos' most brazen attacks on the quality of jobs at Whole Foods and the communities they support," UFCW president Marc Perrone said in a statement. "Too many workers today are already working two to three jobs just to get the hours and benefits they need, and these cuts by Jeff Bezos just made it harder for them. Grocery jobs should be good jobs and one job should be enough to provide for yourself and your family."