ANAHEIM, Calif. - Gov. Arnold Schwarzenegger endorsed a ballot measure requiring public employee union"s to get written permission before using member dues money for political purposes. Democrats viewed the endorsement Saturday at the state Republican Party convention as an attack because Democratic political candidates are the principal beneficiaries of labor union" contributions. The measure, dubbed "Paycheck Protection," will appear on the ballot as Proposition 75. It was funded by advisers to Schwarzenegger but had not previously been part of his "year of reform" agenda. "Public employee union" members should not be forced to contribute to causes, candidates and controversial issues that they don't believe in," Schwarzenegger said. "That isn't a contribution, it's a tax." Republicans have tried for years to pass such measures in California and elsewhere, arguing that union"s unfairly take dues from the paychecks of rank-and-file members — many of them Republicans — and contribute the money mainly to Democratic candidates and causes. To demonstrate the point, Proposition 75 campaign officials produced several union"ized public employees who said they support the initiative. Democrats said the goal of the Republicans is to muzzle the state's labor movement, not protect Republican-leaning workers. "Proposition 75 is the crown jewel of the Bush-Schwarzenegger agenda," said State Treasurer Phil Angelides, who is running for the Democratic nomination to challenge Schwarzenegger next year. "It's what they're after. Everything else is a mask." Schwarzenegger, who announced Friday that he would seek a second term, has seen his popularity tumble in recent months amid criticism from union" activists who have spent millions of dollars on television advertising to discredit his "reform" agenda. The governor spent most of his convention speech pleaing for help in passing his three other major initiatives — extending the probationary period for teachers from two years to five, capping state spending and stripping lawmakers of the power to draw their own political boundaries. "The fact is that the employee union" bosses have simply too much power over the budget, too much power over their members' paycheck and too much power over our state," Schwarzenegger said, drawing loud applause. In 1998, California voters rejected Proposition 226, a similar union" dues measure backed by then-Gov. Pete Wilson.