TweetBernie Sanders, trailing in delegates and running out of time in his quest for the Democratic presidential nomination, told a crowd of supporters Monday evening that it was insulting that Hillary Clinton was refusing to debate him in California."I think it's a little insulting to the people of California -- the largest state," Sanders said, addressing a rally on the astro-turf football field at Santa Monica High School."She is not prepared to have a discussion with me about how she is going to help California address the major crises we face," he said."She's scared! She's scared!" the crowd chanted.Earlier in the day, Clinton, the front-runner for the Democratic nomination, backed out of a debate with Sanders. The two candidates had agreed earlier this spring to hold a debate in May.The last time the pair debated was in New York in April. For Sanders, who also held a rally in East Los Angeles in the afternoon, his criticism of Clinton was a deviation from his standard stump speech. Though he has battled the party's establishment, he has largely avoided direct attacks on Clinton during recent events across California.Still, his disdain over the debate was hard to hide Monday evening. Clinton, he told supporters in Santa Monica, is acting "very nervous lately."