Update: It happened a day early, according to the Associated Press, which called Hillary Clinton the winner of the Democratic presidential primary on Monday night. According to AP’s count, she has now crested the 2,383 delegates she needed:

Clinton has 1,812 pledged delegates won in primaries and caucuses. She also has the support of 571 superdelegates, according to an Associated Press count.
The AP surveyed all 714 superdelegates repeatedly in the past seven months, and only 95 remain publicly uncommitted.
While superdelegates will not formally cast their votes for Clinton until the party’s July convention in Philadelphia, all those counted in her tally have unequivocally told the AP they will do so.

Some of the networks are also calling it for Clinton now, though her campaign prefers to save the celebration for Tuesday, apparently.

The original post follows:

At some point early Tuesday evening, Hillary Clinton will pass the threshold of delegates she needs to clinch the Democratic Party's presidential nomination.

This is a subject of great consternation to rival Sen. Bernie Sanders, who both directly and through surrogates has repeatedly suggested that media outlets who point this out are irresponsibly abdicating their duty to their audiences. But it’s not a complicated issue. If you accept that Donald Trump has clinched the Republican nomination, you should similarly accept that Clinton will seal her party’s nomination on Tuesday.

The sticking point is the Democratic Party’s superdelegates, a big collection of mostly party officials who will roll up to the convention in Philadelphia able to vote for whomever they want. The vast majority of that group has said it plans to vote for Clinton. Since they can’t actually vote until July, though, Sanders insists that their intentions not be considered, and if you don’t consider them, Clinton won’t secure the nomination right after New Jersey votes Tuesday. Instead, she’ll simply be very, very close to clinching after the voting ends, and she’ll make it official at the convention.

Sanders’s argument is weak, at best. There are, in fact, superdelegate-type delegates on the Republican side — people who are “unbound” to any candidate — but the Democrats have far more. In total, about 15 percent of the total delegate pool at the Democratic convention will be made up of people who can vote for anyone they want.

That large percentage is the main reason that Clinton “hasn't been able to put Sanders away,” as that weird recurring assessment of the state of the race phrases it. To get a majority of all of the Democratic delegates without superdelegates — 2,383 — you’d need to win 58.8 percent of the pledged delegates. That means winning about 58.8 percent of all votes cast, thanks to the Democrats’ proportional system. To date, Clinton has won about 56 percent of the votes cast (per U.S. Election Atlas’s tally), just shy of enough to put the race away without superdelegates weighing in.

Trump, on the other hand, has won about 41 percent of Republican votes, but the non-proportional system the Republicans use has allowed him to cobble together more delegates for each state win. But even so, when the Associated Press reported that Trump had sealed the GOP nomination at the end of last month, it was including the votes of those unbound delegates. On Tuesday, Trump will pass the margin of bound delegates he needs to clinch officially — but the AP was very comfortable calling it for him without his having done so.

(Trump was also helped when, after the Indiana primary in early May, his two remaining opponents stopped pretending that they had a shot at winning the nomination. That was the point at which he became the “presumptive” nominee, a status that Clinton could have claimed at any moment had Sanders similarly dropped out.)

For all of his complaints about how the media is on the brink of unfairly handing Clinton the nomination on Tuesday, Sanders has done a remarkably good job of creating the sense that he’s still in this thing. Since March 15, the day that Clinton won Florida, Ohio and North Carolina and took a lead of more than 300 pledged delegates, Sanders has won more states, including a string of seven in late March, bringing him to within 208 pledged delegates.

But since March 15, the point at which it became obvious that he couldn’t catch up, he’s eaten into Clinton’s lead by only about 25 delegates total. Including estimates for Puerto Rico, which voted Sunday — and which Clinton won, giving her a second win in a row — Clinton’s lead is now at an estimated 289 pledged delegates.

In other words, since the New York primary and Sanders’s second attempt to argue that his campaign has the momentum, the two candidates have been about equal in the number of delegates won. And, therefore, about equal in the number of votes.

Sanders has been helped by the sense that state wins are meaningful, when they aren’t. Clinton has a lot of big wins in big states and close wins in smaller ones. Sanders has big wins in small states, where fewer people vote and where he earns fewer delegates.

Perhaps in part because it creates a sense of importance, a number of observers have agreed with the Sanders campaign argument that a win for him in California would hold enormous significance for the race. There’s no practical sense in which that’s true; if he were to win, recent polling suggests that the win would be narrow, essentially splitting the delegates in the state. Sanders hopes to use a win of any size in California as an argument that he’s got the will of the party, but the win will come the same night as a loss in New Jersey and a week before a loss in the District of Columbia — and as Clinton’s lead over Sanders at a national level has started to widen. The rhetorical argument is, at best, iffy.

Which is why it comes back to the superdelegates. Sanders's campaign is desperate that the superdelegates be ignored for now — and that Clinton not be said to have clinched in the way that’s been said of Trump — so that he can theoretically spend the next month telling those same party insider superdelegates that because of a small win in California they should ignore Clinton’s pledged delegate and popular vote leads and make Sanders the nominee. So far, making a similar argument but without the feather that California would add to his cap, Sanders has not managed to convince any of Clinton’s superdelegates of the worthiness of doing so.

And that, at its heart, is the thing. We spent months wondering if Trump would secure the GOP nomination because it looked like that party’s contest might also come down to delegates who could vote for anyone they chose. And on the Republican side, there was reason to think they might: Trump was disliked by party insiders and wouldn’t have a majority of votes from his party’s voters. But a well-timed surge in the Northeast and his party’s rules giving more delegates to the winner came to his aid. Still, a revolution against Trump was, however, conceivable.

A similar revolution by the Democrats against Clinton and against the party majority that voted for her to be the nominee is not conceivable. Sanders hasn’t made much headway at all in the pledged delegate count since March 16, and it’s not clear why a tie in California would change that.

Of course Sanders doesn’t want the media to acknowledge the moment that Clinton will hand him a loss. But, just as the numbers made the result clear for Trump, when New Jersey’s votes come in on Tuesday — unless Sanders wins the state with about 80 percent of the vote — the result will be just as clear for Clinton.