Despite a previous agreement with Bernie Sanders campaign to participate in an additional debate in California, Hillary Clinton campaign had declined an invitation by Fox News for a debate there. 

"We have declined Fox News' invitation to participate in a debate in California. As we have said previously, we plan to compete hard in the remaining primary states, particularly California, while turning our attention to the threat a Donald Trump presidency poses," said the Clinton campaign in a statement released late Monday evening. 

"We believe that Hillary Clinton's time is best spent campaigning and meeting directly with voters across California and preparing for a general election campaign that will ensure the White House remains in Democratic hands," said the statement. 

The Clinton and Sanders campaigns struck an agreement in February of extending the Democratic debate schedule by four more debates. So far, three debates had already been held, with the last one slated before California's primary on July 7. 

Sanders, who had already accepted Fox News' invitation, said in a statement that he was "disappointed but not surprised" by Clinton's unwillingness to debate prior to California's primary. 

"I also would suggest that Secretary Clinton may want to be not quite so presumptuous about thinking that she is a certain winner," said Sanders, referring to Clinton's remarks during an interview with CNN on Thursday that there was "no way" she would lose the nomination to Sanders. 

"In the last several weeks, the people of Indiana, West Virginia and Oregon have suggested otherwise," said Sanders. 

Though facing an uphill battle to catch up with Clinton in delegate count, Sanders with a winning streak had defeated Clinton 11 times in the past 19 Democratic contests.