Voters may get a chance in February to decide whether the Pechanga Resort & Casino near Temecula and three other Southern California Indian casinos should get any bigger.

Racetrack owners, two tribes and a labor union are backing a signature-gathering effort to challenge the agreements that Pechanga and three other tribes signed with Gov. Arnold Schwarzenegger earlier this year.

The agreements would allow the four tribes -- the Pechanga, Agua Caliente, Morongo and Sycuan bands -- to operate up to 7,500 from 2,000 slots that each has now in exchange for a sharing their earnings with the state. That's more slot machines than any casino in Las Vegas operates.

"This is one of the largest expansions of gambling in U.S. history," said Scott Macdonald, a spokesman for the "No on the Unfair Gambling Deals" campaign that opposes the agreements.

The alliance of groups fighting against the casino expansion -- two tribes, including the Pala Band of Mission Indians near Fallbrook, two racetracks and the nation's largest hotel workers union -- is an unusual one.

A spokesman for the campaign supporting the agreements said the alliance is one born of business interests, not ideology.

"(Supporters of the agreements) can issue all sorts of platitudes," said Roger Salazar, spokesman for the Coalition to Protect California's Budget and Economy, funded by the four tribes. "But the fact is these are wealthy gambling interests that don't want competition."

The union wants more favorable election rules to organize casino workers, union officials have said.

With billions at stake, the fight is likely to be fierce, said Robert Stern, a political analyst with the Center for Governmental Studies, a Los Angeles-based research organization that promotes political reform.

Each side has already collected millions for their campaigns.

Backers of the effort to repeal the expansion agreements have raised $5 million. Opponents, including the four tribes, have raised $15 million, according to campaign finance reports filed with the secretary of state's office.

In August, the Pala and Auburn tribes contributed $500,000 each to help gather signatures to overturn the four new agreements, including Pechanga's.

With so much money behind the signature-gathering effort, Stern said, voters will be likely to see the question on their ballots in February.

"If you have enough money, you can qualify just about anything," Stern said.

However, persuading voters to overturn the state's agreements with the tribes will not be as easy, he said. Voters tend to defeat ballot referenda, and the four tribes are likely to spend millions to make sure that happens, Stern said.

Supporters must collect 434,000 signatures by Oct. 8 to put the matter before voters in February. Salazar said the campaign expects to have more than enough signatures to qualify.

The four tribes have said their agreements with the state, also called compacts, would generate more than $9 billion over the next 20 years for the state.

Pechanga's compact, for example, calls for a contribution of $42.5 million to the state each year, up from $29 million under its current arrangement. The tribe would also pay an additional 15 percent of net winnings on the first 3,000 machines it adds and 25 percent of net winnings on the next 2,500 machines.

Tribal governments do not release information on revenues to the public.

A nonpartisan analyst for the state Legislature said the tribe's estimates on how much the state is likely to get from the agreements appears to be unrealistic. And Pechanga officials have said that the tribe does not plan to install all -- or any -- of the 5,500 machines right away.

Still, the tribe is rapidly adding to its complex. It opened a small comedy venue in the casino to augment a larger theater there. Bulldozers are preparing land on the reservation for a golf course.

It is not the first time that tribal casinos have been challenged at the ballot box. In 2004, racetracks and card club owners backed a proposition targeting tribal casinos.

Under that initiative, Proposition 68, all gambling tribes would have been required to pay 25 percent of their profits to the state, or a group of 16 racetracks and card clubs -- including Ocean's Eleven in Oceanside -- would be allowed to operate a total of 30,000 slot machines.

The measure was defeated.

Supporters of the recent effort to overturn the four agreements said they were optimistic because public sentiment has, in their view, turned against casino expansion.

They also said the agreements are unfair to other gambling interests, including smaller tribal casinos and racetracks.

"The way these compacts are structured, it will drive racetracks out of business," Macdonald said. "Racetracks employ 50,000 people. That's a lot of people and we think voters will be concerned."

Two of the tribes fighting in support of the initiative also have agreements with the state allowing them to expand. But Pala's agreement discourages expansion through an increasing fee based on the number of slot machines. Pechanga's fee requires the tribe to pay a percentage of the winnings on each machine.

Howard Dickstein, an attorney for the Pala band, said the agreements set a bad example because they encourage too much growth in casinos and give the state too much oversight authority.

Pechanga Chairman Mark Macarro said in a written statement that he's perplexed as to why Pala would oppose its agreement with the state.

"We are disappointed," Macarro said. "Why a successful gaming tribe would try to block these new agreements and the billions they will generate for California is beyond us, particularly since we respected their recent agreements that gave them unlimited slot machines."

Contact staff writer Edward Sifuentes at (760) 740-3511 or esifuentes@nctimes.com.