Jesse Jackson and Michael Dukakis were wrapping up the long Democratic presidential primary campaign Monday with a final bid for votes in California, the biggest prize in Tuesday's four-state finale.

Vice President George Bush, who locked up his party's nomination six weeks ago, was also campaigning Monday in California, with a series of appearances aimed at calling attention to the drug issue.Dukakis is likely to clinch his party's nomination in the final round of contests Tuesday, which also includes races in New Jersey, Montana and New Mexico. He holds a huge delegate lead over Jackson and is fewer than 300 delegates shy of the 2,081 needed to gain the Democratic nomination.

The Massachusetts governor, who declared his candidacy 13 months ago, got off to a shaky start when he finished third in the season-opening Iowa caucuses in February. But in the months that followed, he methodically felled a field of rivals, one by one.

Only Jackson remains an active competitor. And he is making it clear he will try to remain highly visible even after Tuesday's races.

Jackson says his camp will launch a massive voter-registration drive Aug. 1. He has said he will keep making appearances after Tuesday. And he's putting the party on notice there are issues he's ready to fight for at the convention.

In addition, some of those around Jackson are taking an aggressive tack on the subject of the No. 2 spot on the Democratic ticket. Dukakis has said Jackson deserves to be looked at as a possible running mate but deserves no special consideration.