Here’s the problem in a nutshell: Counting delegates is relatively straightforward because they have already recorded who they are likely to vote for in state primary races. But in addition to regular delegates, the U.S. system has 712 unelected “superdelegates,” and technically, they don’t have to vote until they get to the nomination convention in July.

That means counting superdelegates as backing a specific candidate is a lot less reliable than counting regular delegates as they could theoretically change their vote at any time up until their ballot is cast. Some critics of the AP’s decision to award Clinton the nomination argue superdelegates shouldn’t be included at all. In a statement, the Sanders campaign said:

It is unfortunate that the media, in a rush to judgement, are ignoring the Democratic National Committee’s clear statement that it is wrong to count the votes of superdelegates before they actually vote at the convention this summer. Secretary Clinton does not have and will not have the requisite number of pledged delegates to secure the nomination.

For its part, the Associated Press noted that it didn’t just include all the superdelegates in its Clinton count without checking. AP reporters worked the phones in old-fashioned journalistic style, executives for the wire service pointed out, calling superdelegates and getting them on the record about who they would support. Other news outlets have also reported Clinton as the nominee based on their own reporting, including NBC News.

Said the AP:

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.

Whether the AP wire got superdelegates to declare their support for Clinton isn’t enough to quell some critics, however, because the key point about being a superdelegate is that you can change your votes at any time, regardless of what you told a news service before the convention. In fact, that’s exactly what several dozen superdelegates did in 2008, switching their support from Clinton to Barack Obama at the last minute, as Five Thirty Eight notes in a recent post.

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The question of whether the Associated Press jumped the gun is is more than just a semantic or even a journalistic argument. Supporters of Bernie Sanders have complained that reporting Clinton as the presumptive nominee might convince delegates not to bother voting for him in the remaining primaries on the assumption that the game was already over.

Those kinds of concerns are what prevent media outlets from reporting on the results of election polls until a certain number of them have closed for fear that some voters might see their votes as irrelevant and not bother going to the polls at all. In some countries, it’s actually against the law to report early results from exit polls.

There’s another potential tension in AP doing so by using superdelegates, as Vox explained in a piece:

There’s reason to question whether the AP and NBC News are making the right decision in preemptively declaring the race over based on the superdelegates. By using the superdelegates to declare the race over, these news outlets risk giving greater circulation to the false idea that these party elites have somehow stolen the nomination from Sanders.

Some members of the Clinton campaign have expressed concern that reporting her as the presumptive nominee could hurt her chances in the remaining primaries as well because some supporters might feel that their votes are no longer required.

But one thing is clear: The AP’s decision has increased the already elevated levels of tension between the Clinton camp and the Sanders camp. How that ultimately affects the election itself remains to be seen.