"I am proud to be here with two great unions, because if we are going to rebuild the American middle class, we need to grow the trade union movement," said Sanders.
Sanders brought his message of income inequality, standing in solidarity with striking UC workers -- 40,000 across the state. They're asking the UC system to halt contracts with private companies, overtime-pay after eight hours like other state employees, a path to full-time career positions, and no cuts to benefits.
Sanders said the UC system should be a model employer but is acting more like a corporate employer.
"It must be an employer that respects its workers. It must be an employer that treats its workers with dignity, and it must sit down with its unions and negotiate in good faith," said Sanders.
In a statement, the University of California office of the president said in part: "If Union leaders had channeled as much effort into negotiations as they do into organized theatrics, we'd have a deal by now."
The strike is only taking place Wednesday, and workers will be back on the job Thursday.