(AP) — Officials in San Francisco will vote Tuesday on whether to increase the minimum age to buy tobacco from 18 to 21, even as opponents argue that cities and counties cannot trump California law.

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If the measure is approved, San Francisco would join Boston, New York City and Hawaii in raising the minimum age to buy cigarettes and other tobacco products.

The issue has gained traction nationally as lawmakers try to discourage young people from starting to smoke, especially popular e-cigarettes. A report last year by the Institute of Medicine found that 90 percent of daily smokers first tried a cigarette before 19.

Opponents argue that California law sets a minimum age of 18 and that provision prohibits municipalities from setting a higher limit.

The small city of Healdsburg has suspended enforcing its new tobacco age limit of 21 after a national tobacco retailer group threatened to sue. Santa Clara County, on the other hand, has not.

Thomas Briant, executive director of the National Association of Tobacco Outlets, has urged San Francisco to hold off on voting until the state attorney general can issue a decision. He said 18-year-olds are adults when it comes to voting, serving in the military or signing a contract — and smoking should be no different.

Attorney General Kamala Harris has no legal opinion pending, a spokeswoman said.

San Francisco’s city attorney called the proposed ordinance legally sound. If approved by the Board of Supervisors, it would go into effect June 1.