SAN FRANCISCO—State Finance Director Tom Campbell is stepping down after less than a year in the job to join the campaign team promoting Gov. Arnold Schwarzenegger’s “year of reform” ballot initiatives.

Beginning Thursday, Campbell will take unpaid leave from the Department of Finance to help Schwarzenegger sell his initiatives, which will go before voters in a Nov. 8 special election. The Republican governor wants to cap state spending, strip lawmakers of the power to draw political boundaries and lengthen the probationary period for teachers from two years to five.

“Gov. Schwarzenegger is working to change California for the better, but we are at a historic crossroads,” Campbell said in a statement issued by the California Recovery Team, Schwarzenegger’s campaign arm. “The state has two options: It can continue to spend more than it takes in, or the people can reform the system.”

Schwarzenegger won the 2003 recall election at a time when California was running a multibillion dollar deficit. During the campaign and since taking office, he has insisted that California correct the imbalance between its revenues and its spending. Critics point to his reliance on borrowing to paper over the state’s fiscal shortfall, although he used part of a surplus this year to help pay down some of the state’s long-term debt.

Proposition 76, the so-called “Live Within Our Means” measure, is the centerpiece of Schwarzenegger’s special election agenda. It would give the governor greater authority to make midyear budget cuts, limit state spending to the previous year’s total plus revenue growth and change minimum school funding requirements.

“There is nobody better to help fight for reforms that the state badly needs,” Schwarzenegger said in a statement about Campbell’s switch to the campaign. “We cannot rebuild California until we fix our broken budget system. Tom’s ability to articulate the need for budget reform and his knowledge of the budget make him uniquely qualified to be a fantastic asset to the campaign.”

Campbell’s departure is one of many anticipated out of the governor’s office in the next several days. Pat Clarey, Schwarzenegger’s chief of staff, is expected to become campaign manager for the ballot initiative campaign, while communications director Rob Stutzman will be its chief spokesman.

Schwarzenegger’s once sky-high approval ratings have dropped substantially in recent months, prompting speculation that the exodus of top advisers reflects a desire by the governor to clean house and start anew.

But long-time GOP strategist Ken Khachigian said the migration of Campbell and other top aides to the campaign is more a reflection of how important the special election is to the longterm success of Schwarzenegger’s reform agenda.

“He needs them on the campaign _ that’s the big casino right now,” Khachigian said.

He acknowledged, however, that Campbell’s decision to join the political team was unusual.

“I wouldn’t have figured on the finance director going over, but he’ll be an extremely credible person to talk about budget and spending,” Khachigian said.

A brainy former congressman and Stanford Law professor, Campbell was hailed as a witty and engaging budget whiz when he replaced former Finance Director Donna Arduin last November. But he quickly alienated Democrats, who found his style overly dogmatic and arrogant.

Campbell refused to consider tax increases to close the state’s multibillion dollar budget deficit, instead advocating deep cuts to state programs. In the end, higher-than expected tax revenue this year helped fund many programs, including an additional $3 billion to public education.

Democrats agreed to most of Schwarzenegger’s $117.3 billion budget plan in part so a protracted budget fight could not be used against them during the special election campaign.

In a statement, Assembly Speaker Fabian Nunez, D-Los Angeles, praised Campbell for his work at the Finance Department during a challenging time. Nunez’s spokesman, Steve Maviglio, acknowledged that Democrats had found Campbell difficult to deal with.

“They sent a college professor in to do a bean counter’s job,” Maviglio said. “He’s smart and politically savvy, and those traits sometimes rubbed Capitol insiders the wrong way.”

In addition to being the governor’s lead budget adviser, Campbell also helped promote Schwarzenegger’s agenda. He said the measures were necessary to restore the state to fiscal health.

Campbell served as the governor’s lead negotiator over the summer in a failed effort to strike a compromise with Democrats.

He is expected to leave state government and return to his post as dean of the Haas School of Business at the University of California, Berkeley at the end of the special election campaign.

Also Wednesday, Schwarzenegger named Michael Genest to replace Campbell as acting finance director. Genest served as deputy finance director until last February, when he left to become undersecretary for the state Health and Human Services Agency. Most recently, he had worked with the Department of Corrections and Rehabilitation.