SACRAMENTO, Calif. (AP) — State Senate leader Darrell Steinberg on Wednesday asked for a detailed audit of how counties have spent mental health funding from a 2004 ballot initiative that he co-authored.

Steinberg's involvement after weeks of defending Proposition 63, which raised taxes on millionaires to fund mental health programs, is important because it means an independent review will likely go forward. As president pro tem of the Senate, the Sacramento Democrat is one of the state's most powerful political figures.

His request came after The Associated Press reported that tens of millions of dollars had gone to general wellness programs for people who had not been diagnosed with any mental illness. Two Republican Assembly members last week asked for an independent audit of these programs, which include horseback riding and art classes for the general public.

Steinberg said he read the Assembly members' request and decided that a more wide-ranging audit was in order.

"I'm confident that an outcome-based audit will show people that this has been a tremendous investment, and if there needs to be some changes on how it's implemented or some question of where some of the money has been spent, let's have a real discussion about that, too," he said.

In a letter submitted to the Legislative Joint Audit Committee, Steinberg asked for an examination of the various components of Proposition 63 spending, including prevention, workforce training and innovation. He also called for performance and outcome reviews in a sampling of counties.

Proposition 63 has generated $7.4 billion and funded the creation of about 1,500 new programs. Nearly $1.2 billion has gone to prevention and early intervention programs, while California's overall spending on mental health services has fallen dramatically during the recession.

During an interview Wednesday with the AP, Steinberg called Proposition 63 his most important achievement in public office and said critics should not dismantle it to plug budget holes elsewhere.

Without Proposition 63, he said, California would have even less money for mental health services and none of the innovate programs the tax has funded.

Steinberg has defended the prevention programs but said he hopes the audit will lead to more reporting on program outcomes. For years, the only evaluations have come from county administrators.

"We're going to continue to do everything we can to make sure the gift is spent efficiently and effectively," Steinberg said. "I've got no issue with any critique; it's appropriate, it will make the program better. And it's also an opportunity to educate the public about all the good that's happened."

Steinberg said he hoped the audit would be approved before the end of the legislative session in January.

The two GOP Assembly members who previously requested an audit, Dan Logue of Linda and Brian Nestande of Palm Desert, applauded Steinberg's move Wednesday and said they will combine their request with his.

"What it means is that the committee will move ahead with the audit," Logue said. "I don't think there will be any doubt that it will be done in a timely manner, and there will be answers to our questions."