Some analysts say the move could come back to haunt Schwarzenegger, who has drawn criticism for being too vague on his solutions to California's problems.
Sonenshein said Schwarzenegger's strategy has been to stay away from being too specific on such issues as how to solve the state's budget crisis or fix its electricity system. But the debate may have forced Schwarzenegger to show his hand.
From medical marijuana to the death penalty, the other five major candidates seeking to replace Gov. Gray Davis covered a lot of ground during the first debate - ground that Schwarzenegger will be forced to make up.
"Schwarzenegger's been running his campaign like a movie premiere, which can only work if there's nothing substantive out there," Sonenshein said. "But the bar got raised on Arnold all in one night."
Schwarzenegger, who spent the past two days at events in Southern California, has not fully explained his absence from the debate held near San Francisco, only 34 days before the Oct. 7 election. His campaign managers have given a variety of explanations: He couldn't be two places at once; he had a family event; and he didn't have
enough time to prepare.
Schwarzenegger has been slow to express his viewpoints on a variety of key issues so far. He is fiscally conservative, but says he won't cut education and will raise taxes only in an emergency. He calls himself a moderate on social issues, such as abortion, domestic partnerships and gun control. But he also supported Proposition 187, which attempted to limit state services to illegal immigrants, and said he would rescind a law Davis pledged to sign giving undocumented workers drivers' licenses.
Schwarzenegger spokesman Rob Stutzman played down the candidate's absence, saying the debate in Walnut Creek was a forum largely made up of career politicians. Excluding Davis, who appeared in a shorter question-and-answer session with reporters and ordinary people, only two of the five candidates - Lt. Gov. Cruz Bustamante and state Sen. Tom McClintock - are longtime politicians.
But some say that Schwarzenegger's absence from the debate may be a subtlety that most voters overlook.
"I'm not sure the average voter is there yet," said Sherry Bebitch Jeffe, senior political scholar at the University of Southern California. "The media may see in stark relief what his absence means, but I'm not sure that voters will."
Jeffe said that Schwarzenegger made a mistake not attending the debate, mostly because he gave away a platform to McClintock, a conservative.
"McClintock went a long way last night to solidify himself with the conservative Republican base," she said. "That's a problem for Arnold."
"Before it went into our account we realized that there is a conflict of interest there, that we really don't want to take any money from unions," he said.
The donation from the Association for Los Angeles Deputy Sheriffs was listed on campaign finance records posted Wednesday on the secretary of state's Web site, but Stutzman said the check came unsolicited through a volunteer and was never cashed.
Bustamante, who is leading in the latest poll and is the only well-known Democrat on the ballot, came under fire during the debate for accepting $2 million in Indian gaming money that circumvented current campaign spending limits by funneling most of the cash to an old campaign account.
Even state Democratic Party Chairman Art Torres said yesterday it didn't "smell good" and it left Bustamante vulnerable.
"I just think he opened himself up to a line of attack that he didn't need to," Torres said, adding that the donation still appeared to be legal.
"He didn't need those headaches."