LOS ANGELES, Oct. 16 - As a fifth-grade teacher in Lancaster, Calif., Jeanne Marks feels an occasional need to march into her principal's office and request textbooks or other supplies. She has made the trip often enough, she says, that administrators now roll their eyes when she approaches. She calls herself "a squeaky teacher" for speaking out on behalf of her pupils.

For now, however, Ms. Marks has largely stopped squeaking. A ballot measure before California voters next month would not only extend the time that public school teachers wait to gain tenure, to five years from two, but also change the rules for dismissal, allowing administrators to fire any teacher after two unsatisfactory evaluations without what current rules provide: a 90-day period for improvement and a comprehensive appeals process.

Ms. Marks, who has been teaching for seven years, says that if the measure passes, she will be left more vulnerable to a bad evaluation by any administrator inclined to interpret her "squeaking" as troublemaking.

That is but one objection to the measure, Proposition 74, which has set off a political storm for Gov. Arnold Schwarzenegger, a Republican running for re-election next year. He is promoting Prop 74 as crucial to reforming public schools by weeding out ineffective teachers.

Unions that represent the state's 300,000 teachers are leading the opposition, arguing that the initiative would do little to improve classroom achievement, would scare away new teachers and would encourage school districts to get rid of older teachers, who cost more in salary and benefits.