As legislators battled over the state budget Tuesday, an independent commission voted to slash lawmakers' per-diem payments, car allowances and medical and other fringe benefits by 18 percent.

The vote in Sacramento by the California Citizens Compensation Commission follows the board's vote last May to cut legislator and constitutional state officer salaries by 18 percent as of December 2010.

The salary cuts could save an estimated $2.9 million a year. The non-salary cuts, which the commission wants to impose starting Dec. 1 of this year, would save an estimated $7.8 million over the next six years.

The 18 percent cut would save $500,000 in car lease payments; $2.8 million in lower state contributions to medical and other benefits; and $4.5 million in lower per-diem rates for the legislators.

The commission's latest cuts could be blocked, however, if legislative leaders decide to challenge the commission's authority to regulate cars and per-diem rates as well as salaries and benefits.

"They can either accept it, or fight it," said commission chairman Charles Murray, an insurance businessman who holds the small-business position on the board.

He said pro-bono attorneys are "in line" to back up the commission.

Bill Curtis, chief counsel of the Department of Personnel Administration, warned the commission Tuesday during its meeting that members had no jurisdiction to set either the per-diem rate or car payments.

Curtis' office gave commissioners a legal opinion advising that they control only salaries and "insured benefits," such as medical, dental, disability and legal services that require premium payments.

Travel costs don't fall under their legal purview, according to the opinion.

Murray said he disagreed.

He said his research into the origins of the commission showed that his board has the power to set the "package" of compensation given to legislators and state officers.

"In the private sector, employers negotiate with employees and say, 'Here's the package,' " Murray said. "In the public sector, I think it should be the same way."

Senate President Pro Tem Darrell Steinberg's aides couldn't reach him for comment because he was in budget meetings.

Shannon Murphy, a spokeswoman for Assembly Speaker Karen Bass, said in a statement that Bass "declined last year's per diem increase for legislators."

That raise was approved by the Victims Compensation and Government Claims Board, which has been authorizing per-diem rates.

Sen. Gil Cedillo, D-Los Angeles, said the commission's decision "was a sign of the times."

"A lot of the focus is on us," Cedillo said. "It's a natural reaction because of our high visibility."

During their meeting, commissioners discussed how state workers had been forced to take pay cuts through furloughs.

Some commissioners said they thought they should aim to bring down legislators' pay by similar percentages.

"The state of California is in dire straits now," said Ruth Lopez Novodor, the commission's nonprofit-organization representative.

Former Auburn Mayor Kathy Sands, the general-population representative, said the per-diem rate legislators receive now is "unjustifiable."

The daily sums can add up to $30,000 to $35,000 a year.

"I feel that this is a lot of money," Sands said.

"They don't have to fill out expense forms to justify anything," she added, saying it's possible to get a room and meals in Sacramento for less than $173 a day.

Murray said he was troubled when a speaker told commissioners that the per-diem rate for state employees on business in Sacramento is capped at $124 a day, almost $50 less than for legislators.

"Senators get a better room?" Murray asked.

Scott Somers, who holds the commission's compensation-expert seat, said the vote to reduce health benefit payments was not meant to be "punitive" toward legislators or state officers.

But to help the state, lawmakers will have to pay more for premiums themselves, he said, or the state can look for cheaper plans.

Commissioner John Stites, a Los Angeles County sheriff's sergeant and one of the labor representatives, said it would be too complicated to try to cap the unlimited spending on gas that legislators now get for their cars.

"They have to have some allowances to do their jobs," which includes visiting constituents in districts of varying sizes, he said.

Right now, the state limits car leases to $350 for senators and $400 for Assembly members. Lawmakers shoulder 10 percent to account for personal use.

Cutting those costs, Sites said, doesn't add up to "substantial savings" for the state.

"But we can use that (money) somewhere else," he said.

Commission members did not discuss eliminating lawmakers' lease payments altogether.

Call Susan Ferriss, Bee Capitol Bureau, (916) 321-1267. Steve Wiegand of the Bee Capitol Bureau contributed to this story.