Hillary Clinton finish the weekend with a victory in the Puerto Rico Primary. With 67 delegates available, both sides made the effort to campaign in the larges US territory. Clinton beat Sanders solidly by about 20 points. She won 36 delegates to 24 for Sanders. Clinton also already had six of the seven superdelegates pledged to her with one still remaining uncommitted. Only about 60,000 voters turned out to vote.
The victory in Puerto Rico puts Clinton a mere 27 delegates away from an absolute majority. With California, New Jersey, New Mexico, Montana, North Dakota, and South Dakota poised to distribute 806 delegates on Tuesday, Sanders could win 95% of the vote in every State and still not prevent Clinton from reaching a majority.
Sanders is still pinning his hopes on the fact that Clinton's victory is dependent on superdelegates. Without counting superdelegates, who can change their vote an any time, Clinton has only 1809 delegates. Even if she wins 60% of the remaining delegates, she would still be short of an absolute majority counting only pledged delegates.
Sanders strategy seems to be to win California, which he may possibly do, but only by the most narrow of margins, that call on the superdelegates to change their votes since he is the most popular toward the end of the campaign.
This seems highly unrealistic for many reasons. First, Clinton leads sanders by any popular measure. She has won more pledged delegates, States, and total primary votes. Second, she is the establishment candidate. Third, these delegates already pledged to Clinton because they support her candidacy. Sanders is asking the Democratic Party establishment to change their committed votes to support a non-establishment candidate who primary voters have rejected by any reasonable measure. That will not happen.
Sanders' real card is the fact that he can still be a spoiler. If he screams and shouts that the Democratic Party is unfair, and perhaps even endorses a third party like the Green Party candidate, he could siphon off enough of his supporters to kill Clinton's chances against Trump. On the other hand, if he plays nice and tells his supporters that we must all come together to defeat Trump, that will go a long way toward uniting the party.
The only question is how high a price Sanders can exact for his support. He could demand to be on the ticket as VP (highly unlikely). He could insist Clinton choose a VP from a list of acceptable candidates. He could insist on changes to the Primary system for the next elections. He could demand the appointment of a new acceptable DNC Chair, or he could just demand some control over the Party platform, which everyone pretty much ignores anyway.
There is no real path to prevent Clinton from obtaining a majority of delegates. The only question now is whether Sanders can support her in a meaningful way.