LOS ANGELES (AP) - Entering a fight over union rights that could have national implications, Sen. John Kerry warned Thursday that a ballot initiative backed by Gov. Arnold Schwarzenegger could tip the balance of democracy by muzzling the voice of working people. Proposition 75 would force public employee unions, such as those representing teachers, firefighters and prison guards, to seek written permission from members before using dues for political purposes. Kerry, speaking outside a downtown firehouse, said the initiative would condemn workers to "a completely unfair system." The proposal "represents part of an ongoing effort by the Republican Party to...