Local business advocacy groups came together in a rare joint news conference Tuesday to declare their opposition to a state bill that would penalize large employers whose workers enroll in Medi-Cal.

Kern County business and political leaders called Assembly Bill 880, authored by Assemblyman Jimmy Gomez, D-Los Angeles, an unfair "double tax" that would disproportionately burden agricultural operations, thereby limiting local job growth.

"If AB 880 were to pass, expect your grocery bills to increase," Ben McFarland, executive director of the Kern County Farm Bureau, said at a morning event at the office of the Greater Bakersfield Chamber of Commerce. He was joined by Bakersfield City Councilman Terry Maxwell as well as staff to county Supervisors Zack Scrivner and David Couch and representatives of the chamber and the Kern County Taxpayers Association.

Under the bill, most California businesses with 500 or more workers would face a penalty if their employees working more than eight hours per week enroll in Medi-Cal, the federally supported, state-run program designed to provide health insurance for poor people.

The penalty would amount to 110 percent of the cost large employers pay to provide their employers with medical coverage; that money would go into a fund supporting Medi-Cal.

The bill would prohibit employers from forbidding their workers from enrolling in Medi-Cal or other public health insurance programs. Also, employers would not be allowed to request information about worker eligibility for public health coverage or take action against workers who sign up for such programs.

Business advocates at Tuesday's event noted that many agriculture-related jobs are seasonal or part-time by nature, and so the bill would hit Kern's farming industry particularly hard.

Assemblyman Gomez's Sacramento staff did not respond to a request for comment Tuesday. But the state's analysis of the bill says Gomez proposed the bill in order to "close a loophole" in the Affordable Care Act, the health insurance reform legislation informally known as Obamacare. It says Gomez wanted to make sure employers don't shift the cost of providing employee health coverage to the state.

The bill is supported by labor unions and opposed by large retailers and restaurant chains, as well as the California Chamber of Commerce. It passed the Assembly's health committee in April and its appropriations committee in May.

The president and CEO of the local chamber of commerce, Cindy Pollard, said her organization recently sent a letter to Gomez expressing concern about the bill.

In recent years, the chamber has very rarely called news conferences to call attention to proposed legislation. Usually, Pollard said, the organization makes phone calls, writes letters and arranges face-to-face visits with lawmakers.

She said to expect more such events.

"If it's important to our members," she said, "it's important to us."