Arnold Schwarzenegger's (search) campaign said Thursday it would return a $2,500 check from a law enforcement union, a donation that ran counter to the actor's pledge not to accept money from special interests.

The donation from the Association for Los Angeles Deputy Sheriffs (search) was listed on campaign finance records posted Wednesday on the Secretary of State's Web site.

Campaign spokesman Rob Stutzman said the check came unsolicited through a volunteer.

"Once a check is received, it has to be reported," he said. "But it was not cashed, and it will be returned."

He said Schwarzenegger nevertheless was proud to have the backing of rank-and-file law enforcement.

Schwarzenegger said he would not take money from anyone when he entered the campaign to replace Gov. Gray Davis (search) in the Oct. 7 recall election, but later accepted checks from wealthy individuals and companies. He subsequently said he wouldn't take money from special interests, such as unions or Indian tribes with gambling casinos.

His pledge to return the law enforcement check came as he made an appeal for help in registering new voters during a brief speech to a cheering crowd in Riverside, 60 miles east of Los Angeles.

"We are going to take this government back on Oct. 7, but alone I cannot do that," he said. "I need your help, so let's all work together to make sure that everyone registers. Register all the people and make sure that they vote."

The remarks came a day after Schwarzenegger was a no-show during a debate in which five top candidates in the race clashed over how they would lead the state and the best way to solve California's budget crisis.

While little was said of Schwarzenegger's absence, most of his competitors criticized him afterward for failing to engage in a discussion of issues that covered the spectrum.

"I don't believe that a candidate who is not willing to discuss his views in the presence of the other candidates can be taken seriously," said Republican state Sen. Tom McClintock (search), who may have the most to gain by Schwarzenegger's absence.

Stutzman said Schwarzenegger will participate only in the Sept. 24 California Broadcasters Association (search) debate in Sacramento.

Five candidates participated in the debate: McClintock, Lt. Gov. Cruz Bustamante (search), columnist Arianna Huffington (search), former baseball commissioner Peter Ueberroth (search) and the Green Party's Peter Camejo (search).

Before the debate, a contrite Davis led a question-and-answer with reporters and voters, saying he had not acted soon enough to deal with the state's energy crisis and pledged to keep in better touch with the people.

"I understand people are angry. I understand that people's lives are not as good as they were two years ago," said Davis, employing a theme he has repeatedly used throughout the recall campaign.

The forum offered the broadest look yet on where the candidates seeking to replace Davis stand on issues. The only issue on which they agreed was support for legalization of medicinal marijuana.

Huffington, an independent, said her administration would favor teachers over prisons. Camejo said the state needed to become a leader in renewable energy. And Ueberroth had a unique take on solving the budget crisis: "I'm about locking up the Republicans and Democrats the first day until we have a budget that works," he said. "It's not going to be pretty."

Some analysts said Schwarzenegger's absence could hurt him and bolster McClintock, the more conservative candidate who seemed to reinforce the support he has received at the polls.

"I think the big loser here was Arnold, you might see that Arnold has slipped and McClintock has improved," said Brian Janiskee, political science professor at California State University at San Bernardino.

During the debate, Bustamante was criticized for taking advantage of a loophole in campaign finance law that allowed an Indian tribe to pledge $2 million to his financially struggling campaign.

Huffington, an independent, said Bustamante had made a mockery of campaign finance laws, which allowed him to circumvent new contribution limits by accepting the bulk of the money in an old campaign account. "This is nothing but legalized bribery," Huffington said.

"Tell me how you really feel," Bustamante replied.

Ueberroth acknowledged that he wasn't the smoothest candidate in front of a camera and didn't have all the answers, but said he would improve as the campaign progressed.

"Frankly, these people — several of the candidates — have been in Sacramento for 20 years," he said Thursday on the KABC radio talk show "Ken & Company." "They've been saying the same things. So I know the rules now, and next time I'm going to have a little more fun with it."