Washington (AP) -- Lifted by a big win in Puerto Rico and a burst of late support from Democratic superdelegates, Hillary Clinton has commitments from the number of delegates needed to become the Democratic Party's presumptive nominee for president.
She reached the required 2,383 delegates on Monday, according to an Associated Press count.
Here's a look at the count and how the AP determined Clinton has enough delegates to become the presumptive nominee, besting her primary rival, Vermont Sen. Bernie Sanders.
WHAT'S THE COUNT
In the primary elections and caucuses, Clinton has won 1,812 pledged delegates. Sanders has won 1,521. That gives her a lead of 291.
That is far more than the 131-delegate lead that then-Sen. Barack Obama held over Clinton when he clinched the Democratic nomination on June 4, 2008.
Among superdelegates, Clinton has the support of 571. Sanders has the backing of 48. That gives Clinton a lead of 523 superdelegates.
Overall, Clinton has 2,383 delegates, Sanders 1,569.
WHAT COMES NEXT?
Two days of election contests remain. On Tuesday, voters in six states — California, Montana, New Jersey, New Mexico, North Dakota and South Dakota — head to the polls, with 694 delegates up for grabs. The Washington, D.C., primary is a week later.
Even if Clinton were to lose all the remaining contests, she would continue to comfortably pad her delegate lead above the 2,383 threshold. That's because Democrats award pledged delegates in proportion to the vote, so even the loser gets some.
Sanders, meanwhile, would need to win 814 delegates to reach 2,383. Only 813 pledged delegates and uncommitted superdelegates remain.
HOW AP COUNTS SUPERDELEGATES
Of the 4,765 total delegates to the Democratic National Convention, 714 are superdelegates. They are all party officials, governors and members of Congress who may vote for the candidate of their choice, regardless of the outcome in their state's primary or caucus.
The AP surveys the superdelegates throughout the primary season, over months and months, to track whom they plan to support at the July convention.
If a superdelegate tells the AP he or she plans to unequivocally support a certain candidate at the convention, that's added to the candidate's tally.
Those who decline to answer, who say they have yet to make a decision or express any reservations are listed as uncommitted.
The AP tally can be found at: http://elections.ap.org/content/delegate-tracker
WHY COUNT SUPERDELEGATE VOTES?
Sanders argues superdelegates should not be counted, since they don't formally cast their votes until the national convention. He intends to try to win over those who back Clinton by making the case before the party meets in Philadelphia that he would be a stronger general election candidate against presumptive GOP nominee Donald Trump.
But in the AP's survey, which began in late 2015, no superdelegate has flipped support from Clinton to Sanders. None has suggested that could happen.
Since their creation in 1982, superdelegates have rarely strayed from their original endorsements — unless there is a change in the pledged delegate tally. In 2008, some superdelegates flipped from Clinton to Obama after he overcame her early lead in pledged delegates.
The majority of superdelegates have always sided with the winner of the most pledged delegates, which in this election is Clinton.
The Sanders campaign acknowledges it is unlikely he can switch enough superdelegates from Clinton to overtake her lead among the party insiders unless he is able to win a majority of the pledged delegates.
Clinton remains far ahead on that front. She is on track to safely end the primary season with a majority of pledged delegates even if she loses all six states on Tuesday and in Washington, D.C., the following week.
AP ON THE DELEGATE COUNT
AP Senior Vice President and Executive Editor Kathleen Carroll said in a statement Tuesday:
"AP concluded that Hillary Clinton had enough delegates to clinch the nomination after a painstaking but very straightforward exercise.
"By Monday evening, 571 superdelegates had told us unequivocally that they intend to vote for Clinton at the convention. Adding that number to the delegates awarded to Clinton in primary and caucus voting to date gave her the number needed to be the presumptive nominee.
"That is news, and reporting the news is what we do.
"Nothing in that discourages or prevents voters in six states from exercising their right to go to the polls today and cast their ballots."
IS THAT ALL?
When it comes to winning the nomination, only delegates matter. But by two other measures, Clinton also comes out on top.
She has won 29 states and U.S. territories, to 21 for Sanders. She has also won more than 13.6 million votes, compared with nearly 10.6 million for Sanders.
Clinton's big victories across the South and in the biggest states — such as New York, North Carolina, Ohio, Pennsylvania and Texas — provided her with that wide edge in raw vote and pledged delegates.
The Vermont senator tended to fare better in smaller states and those with caucuses, which limited his overall gains due to their smaller pool of delegates and voters.
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