Former president Bill Clinton, left, walks with his wife, Democratic presidential candidate Hillary Clinton, right, in a Memorial Day parade May 30 in Chappaqua, N.Y. (Mel Evans/Associated Press)

NEW YORK -- Hillary Clinton has upended her campaign schedule, adding more stops in California, in an effort to prevent an embarrassing loss there to Bernie Sanders, her rival for the Democratic presidential nomination.

Clinton originally planned to campaign for two days this week in New Jersey, but at the last minute canceled an event on Thursday and will instead return to California for a five-day swing.

The schedule change comes as Sanders has barnstormed California, not leaving the state in more than a week. Meanwhile, a recent poll found the race closing significantly. Clinton's lead over Sanders had narrowed to just two points.

Details are scarce, but Clinton now plans to hold events in California from Thursday until the day before the state's June 7 primary.

After a narrow victory in Oregon on May 17, Democratic presidential candidate Bernie Sanders is vowing not to give up in the fight against rival Hillary Clinton for his party's nomination. (Reuters)

Although she probably will secure enough delegates to clinch the nomination before polls close in California that day, a loss in the nation's most populous state would be an embarrassing end to the contentious Democratic primary.

Sanders has poured virtually all the resources that remain in his campaign into the effort to win California. There are 475 pledged delegates at stake there, and Sanders has said that his goal is to secure as many of them as possible to make the case at the Democratic convention in Philadelphia that he would be the stronger general-election candidate.