Hundreds of Uber and Lyft drivers rallied in San Francisco on Tuesday in support of a state bill that would make it more difficult for companies to classify workers as independent contractors. The rally, which convened outside Uber’s headquarters on Market Street, was organized by a group called Gig Workers Rising, which is partly supported by labor giant SEIU.

The bill in question, AB5, is an outgrowth of a May 2018 decision by the California Supreme Court in favor of workers for a document delivery company called Dynamex Operations West that were seeking employment status. The drivers for the delivery service first brought their case over a decade ago, arguing that they were required to wear the company’s uniform and display its logo while providing their own vehicles and shouldering all of the costs associated with the deliveries. The decision is seen as having potentially enormous consequences for companies like Uber and Lyft, which classify their drivers as independent contractors.

The bill’s sponsors say they want to stop the misclassification of workers

The bill’s sponsors say they want to stop the misclassification of workers. AB5 would require companies to use a legal standard called “the ABC test” when determining employment status:

A): The worker is “free from the control and direction” of the company that hired them while they perform their work. (B): The worker is performing work that falls “outside the hiring entity’s usual course or type of business.” (C): The worker has their own independent business or trade beyond the job for which they were hired.

If passed, it could make Uber and Lyft responsible for traditional employment benefits like paid sick leave, unemployment insurance, and workers compensation. The ride-hailing companies, meanwhile, prefer less drastic measures, like so-called portable benefits that drivers can take with them from job to job. The companies claim they want to preserve drivers’ “flexibility” to set their own hours and work for multiple platforms.

The bill passed the California State Assembly in May 2019. It’s now up to the Senate Appropriations Committee to determine the financial costs of the legislation before bringing it to the full Senate for a vote. California Gov. Gavin Newsom has yet to say if he would sign it into law, leaving the bill’s future in question.

The rally drew hundreds of drivers, as well as one 2020 presidential candidate: South Bend, Indiana Mayor Pete Buttigieg. “I’m here because where I come from, ‘gig’ is another word for ‘job’,” Buttigieg said in a video tweeted by Gig Workers Rising. “They say these technology companies are the future of the American workforce. I think that might be right. So do we want a future where there might be no protections, no union, and workers aren’t treated as workers? Or do we want a future with justice?”

Buttigieg is walking a fine line of voicing support for protesting drivers while also courting top executives at the companies that employ them. In May, he headlined a fundraiser in Oakland co-hosted by Uber executive Chelsea Kohler, the rideshare company’s director of product communications, according to The Daily Beast.

Other 2020 candidates have endorsed the bill as well, including Sens. Elizabeth Warren (D-MA), Kamala Harris (D-CA), and Bernie Sanders (I-VT).