And a top McCain aide said the Arizona senator would have a hard time winning the Republican presidential nomination without the big state's 162-delegate prize.

"It's possible to win the nomination without California's delegates, but I wouldn't go to Vegas with those odds," McCain's political director John Weaver told The Associated Press.

Though McCain said he didn't want "some big delegate fight," his advisers said they are considering all options -- including a challenge to the delegate-selection process or a lawsuit.

Another option, aides said, might be to pressure the party into granting McCain a portion of the delegates should he win the popular vote but Bush wins a majority of Republican Party members. McCain himself laid the groundwork for that political case Tuesday.

"If there's a split decision, that's going to be a debate that's taking place within the Republican Party," the Arizona senator said. "Do they want somebody who won the majority or do they want somebody who only won Republican votes?"

The dispute arises out of a complicated state election law that requires state officials to report dual results: totals that include all voters and a separate account for the winner among only GOP voters.

Delegates to the Republican National Convention are to be awarded to the winner of the GOP-only count.

The McCain camp's comments raised a potentially divisive new issue in the GOP presidential race, roiled in recent weeks by charges of negative campaigning and by the Arizona senator's own criticism of religious right leader Pat Robertson.

Polls show McCain and Bush in a close race in California's open primary, with Bush holding a wide lead among Republicans. A split result could leave Bush claiming all of the state's 162 delegates even as McCain won the broader vote.

Seeking a boost in the state, McCain switched gears Tuesday and said he would appear by satellite in a Republican debate Thursday. McCain had earlier said scheduling conflicts would prevent him from appearing but he was peppered with questions.

"We'll change my schedule, cancel events in New York, land somewhere on the way back from New York and engage in a satellite debate," said McCain. Bush aides said they also were considering appearing via satellite.

All three GOP candidates signed a pledge to abide by the results of the delegate-selection voting, but senior McCain aides said they would protest in any state where they felt the process was manipulated unfairly.

One potential would be to formally challenge the delegate-selection process within the Republican Party. That's a less likely option, in part because Bush controls many of the levers of power within the party.

McCain's lawyers said they were closely watching their legal options, too.

In a move that could spare McCain himself from filing a lawsuit, a former state lawmaker has filed a legal challenge to the state law that established the split primary format.

McCain's advisers, meanwhile, laid the groundwork for a political case against a split decision.

Campaign manager Rick Davis said Republicans would be sending the worst possible message if McCain wins a popular vote but doesn't come away with any delegates.

"It does raise red flags as to how delegates are allocated in California because of the exclusion of independents who would choose to support Republicans," said Davis.

McCain's aides were choosing their words carefully, not wanting to throw down a gauntlet to Republicans that would preclude compromise. One example cited was New York, where Bush allies had moved to keep McCain off the ballot in that state.

When critics argued that was unfair, Bush relented in the face of public pressure and dropped his challenge, allowing McCain on the ballot.

McCain said, "If they want to choose a candidate who can't win the popular vote in the state of California, that's a decision they would have to make. Obviously we would argue our case, but I don't think we'd want to have some big delegate fight."