“We need a real change in this country,” Mr. Sanders said to a cheering crowd at the restaurant, Hamburger Mary’s, in West Hollywood, “and we need a government which represents all of us, not just the 1 percent.”

During a news conference on Saturday in Los Angeles, Mr. Sanders said it would be wrong for Mrs. Clinton to claim victory on Tuesday based on her total delegate count. News media outlets should not call the race, he said, unless she reaches the threshold with only pledged delegates.

“It is extremely unlikely that Secretary Clinton will have the requisite number of pledged delegates to claim victory on Tuesday night,” Mr. Sanders said. “Now, I have heard reports that Secretary Clinton has said it’s all going to be over on Tuesday night. I have reports that the media, after the New Jersey results come in, are going to declare that it is all over. That simply is not accurate.”

Mrs. Clinton leads Mr. Sanders in both pledged and total delegates.

In a sign of his campaign’s urgency to win in California, Mr. Sanders criticized the Clinton Foundation during an interview on Sunday on CNN’s “State of the Union.”

“If you ask me about the Clinton Foundation, do I have a problem when a sitting secretary of state and a foundation run by her husband collects many millions of dollars from foreign governments, governments which are dictatorships?” Mr. Sanders said.

“You don’t have a lot of civil liberties or democratic rights in Saudi Arabia,” he told the interviewer, Jake Tapper. “You don’t have a lot of respect there for opposition points of view for gay rights, for women’s rights. Yes, do I have a problem with that? Yes, I do.”

Mr. Sanders and Mrs. Clinton spent Sunday campaigning in California, where polls indicated a tight race. Mrs. Clinton and Mr. Clinton visited black churches, appealing to a demographic that had given her important support in past nominating contests.