SAN FRANCISCO - San Francisco has a long history of bold public health and environmental stances, going after everything from plastic bags in grocery stores to cigarettes to sugary drinks.

The latest target: Ronald McDonald.

A proposed city ordinance would ban McDonald's from putting toys in Happy Meals unless it adds fruit and vegetable portions and limits calories. The proposal would apply to all restaurants, but the focus has been on McDonald's and its iconic Happy Meals.

Supervisor Eric Mar said he proposed the law to protect the health of his constituents, but McDonald's has waged an aggressive fight to block the measure. A battery of McDonald's Corp. executives showed up at city hall to argue that the legislation is a heavy-handed effort that threatens the company's decades-old business model and the free choice of its customers.

The proposed Happy Meal law is just the latest in a string of San Francisco ordinances aimed at regulating public health. The city recently expanded a law banning tobacco sales in pharmacies to include grocery stores and big-box stores that also have pharmacies.

Mayor Gavin Newsom signed an executive order earlier this year banning sweetened beverages like Coca Cola and Pepsi from vending machines on city property. Local leaders considered but ultimately abandoned laws recently that would have imposed a fee on businesses that sell sugary drinks and alcohol.

Newsom has slowed down in his support of some health measures after he was attacked by his opponent in next month's lieutenant governor's race, Lt. Gov. Abel Maldonado, for being the "food police." Newsom vetoed the alcohol and soda fees, and he's indicated he'll do the same for Ronald McDonald.

The Board of Supervisors could overturn a veto but needs the votes of eight of 11 supervisors to do so.

Tony Winnicker, a Newsom spokesman, has said the mayor was opposed to the measures in part because of their negative impact on local businesses.

"The mayor is always open to argument and evidence about a better way - he's not ideological, he's not wedded to one approach," Winnicker said. "This is not the time to be considering new fees and taxes that would put San Francisco at a disadvantage to other counties around the state."

Mar said he expected his Happy Meal bill to pass out of committee Monday and receive a vote by the full Board of Supervisors later this month.

McDonald's vice president for nutrition and menu strategy, Karen Wells, said that denying a toy to a child would undermine the authority of parents to decide what their children should eat and would be difficult to execute.

"It's different from what we're doing today and different from what we've done for 25 years, successfully," Wells said.

Responded Supervisor Sophie Maxwell in an exasperated voice, "Just because it's different does not make it necessarily difficult. I mean, McDonald's is an amazing institution. It's been around for many years ... because it's able to change and to adapt to new circumstances and new things that people are eating so I think I have a lot more confidence in McDonald's, I guess, than you do."

Cynthia Goody, McDonald's nutrition director, said there was no evidence that childhood obesity would be reduced by requiring a fruit or vegetable with all meals.

In response, a supervisor asked what mix of foods would lower childhood obesity. Goody said she would need to conduct more research to provide an answer.

The Happy Meal ordinance is not all surprising given San Francisco's famously liberal leanings.

"San Francisco has a reputation - and it's well deserved - of being a very progressive city," said Alex Clemens, founder of Barbary Coast Consulting, a local political communications firm. "With that comes naturally, hand in hand, a reliance on government to encourage thoughtful change - that's just tradition."