SAN DIEGO (NEWS 8) - University of California service workers continue to picket Tuesday as they carry on into their three-day statewide strike.

More than 4,000 workers walked the picket line Monday across San Diego. That number is expected to grow Tuesday because several University of California nurses, pharmacists and radiologists have joined the strike to support service workers' demands for higher wages.

The strike was called last week by American Federation of State, County and Municipal Employees Local 3299 after the union and the university could not agree on a new contract.

Some employees say there’s a huge gap between the university's highest paid and lowest paid workers. They also claim that female and minority service and patient care workers make significantly less than their white male counterparts.

University officials say service workers are already paid at or above market rates and that it cannot afford the nearly 20 percent pay raise over three years the unions is demanding.

UC San Diego hospitals have had to train hundreds of replacement workers for Tuesday and Wednesday and about 200 elective surgeries have been postponed.