Gov. Arnold Schwarzenegger's fiscal reform plan won the backing Thursday of the state's largest labor group, adding to a growing roster of endorsements for a $15 billion bond measure that the governor has painted as critical to avoiding steeper budget cuts.

The California Labor Federation, the state AFL-CIO with more than 2 million members, endorsed both Prop. 57 and Prop. 58, the bond measure and proposed new limits on state spending.

Art Pulaski, executive secretary-treasurer for the group, said it would fund mailers and marshal precinct walkers before the March 2 vote.

"This is about solving the economic crisis the state faces right now. We want to be a part of the solution," he said.

A statewide poll last month by the Public Policy Institute of California showed an uphill climb for the bond measure, with 44 percent opposing it, 35 percent supporting it, and 21 percent undecided.

But in recent weeks, organized opposition has shriveled, while Schwarzenegger's "fiscal recovery plan" has picked up support, some of it grudging, on both sides of the political aisle.

Sen. Tom McClintock, R-Thousand Oaks, and state Treasurer Phil Angelides, a possible Democratic candidate for governor in 2006, remain the most vocal opponents, but no funded campaigns have emerged.

In the meantime, the campaign for the two bond measures is slated to launch its first TV ads next week featuring Schwarzenegger and state Controller Steve Westly, a Democrat.

The campaign is on pace to meet its goal of raising at least $8 million, said spokesman Todd Harris. Later this month, Schwarzenegger has a $50,000-a-head fund-raiser planned in New York.

"It's a very powerful message to send to the public to say you have the active support of both labor and the Chamber of Commerce," said Harris. "We've been making a full-court press ... to showcase the bipartisan support."

The labor endorsement marks an unusual political alliance after a bitterly fought election in which labor spent millions of dollars to defeat the gubernatorial recall that vaulted Schwarzenegger into office. Pulaski said he spoke with the governor after a unanimous vote of union leaders.

"We're nonpartisan. We will work with anybody who wants to work with us on issues that protect working families," said Pulaski.

The labor group took its stand after holding a conference call with union leaders Thursday. On the call, Senate President Pro Tem John Burton, D-San Francisco, urged their support.

The union's impact will depend on how much it throws behind the campaign, said Larry Gerston, a San Jose State political scientist.

"There are endorsements and there are endorsements. It remains to be seen what kind of firepower they will bring," said Gerston. "What they really have to do is arouse the electorate."

More so, said Gerston, because of a cluttered ballot that features four state ballot measures and the Democratic presidential primary.

Neither the state Republican Party nor the Democratic Party has endorsed Schwarzenegger's plan. A Republican insider said the party will probably vote to support it at its convention Feb. 20-22.

The Democratic Party continues to hold off, though some Democratic leaders have come on board recently, including House Minority Leader Nancy Pelosi, D-San Francisco, who called the bond plan "a necessity, unfortunately."

Schwarzenegger boasted this week that he has won the backing of U.S. Sen. Dianne Feinstein. But Feinstein spokesman Howard Gantman would only say that she would announce her position "in the coming days."