In the battle for primary votes, Hillary Clinton and Bernie Sanders are locked in a tight battle.

But you wouldn't know it to look at the superdelegates. In the unseen battle for these party insiders, Clinton has an overwhelming lead. Of the 712 Democratic superdelegates, 449 (or around 63 percent) currently support Clinton, according to the latest Associated Press survey of superdelegates. Only 19 support Sanders. (AP did not reach 62 superdelegates, and 182 remained uncommitted or undecided.)

Taking superdelegates out, Sanders has a 36 to 32 lead, based on the vote in Iowa and New Hampshire. But this superdelegate advantage is not only a huge lead for Clinton but a big gain as well. Since the AP's November survey, her total has jumped 90 delegates. Sanders, meanwhile, has risen 11, from 8 to 19.

Of course, Clinton also had a big superdelegate lead the last time she ran, but went on to lose the nomination. As of January 2008 — shortly into the nominating process but still before Super Tuesday — she likewise maintained a huge lead, of 201 to Barack Obama's 89 and John Edwards' 40, according to the AP.

Then, in February 2008, Obama was starting to quickly pick up superdelegates, while Clinton had started to lose some to his side.

This time around, she is maintaining strong support among the party's "establishment" thus far, despite the fact that the race is tight in some primaries and caucuses.

Superdelegates consist of some well-known names — members of Congress and former presidents (Bill Clinton is one), for example — and many party insiders who most Americans don't know — state party leaders and Democratic National Committee members, for example.

While the non-super delegates are allocated based on how people vote in the various state caucuses and primaries, the superdelegates are "unbound," meaning they can choose who they want. And thus far, they have overwhelmingly chosen Clinton. She has the support of 68 percent of superdelegates right now.

This can make for delegate counts that don't quite seem to make sense considering vote totals. In New Hampshire, where Sanders won the primary by a 22-point margin, both he and Clinton have 15 total delegates. While he won 15 of the state's 24 non-super delegates, she has 6 of the 8 superdelegates in her corner.

Some Sanders supporters, upset about this system, have taken to contacting superdelegates, as the AP reports.

And one petition, declaring that "race for the Democratic Party nomination should be decided by who gets the most votes, and not who has the most support from party insiders," asks superdelegates to "pledge to back the will of the voters." Currently, that petition has more than 161,000 signatures.

The fact that the superdelegate system gives the party outsize influence clearly upsets many Sanders supporters, but giving the party outsize influence is the point of the system.

Superdelegates were created in 1982 to "improve the party's mainstream appeal" by giving party insiders more influence and reduce that of "activists," as Brookings Institution's Thomas Mann and AEI's Norman Ornstein wrote in 2008, when Clinton and Obama were also battling it out for superdelegates.

Ornstein and Mann laid out several arguments for the superdelegate system: it's a sort of "peer review" to choose the most electable candidate, they wrote, and promotes a sense of unity, making "stronger ties between the party and its elected officials."

Of course, in a tight race, that "unity" argument is probably hard to see from a voter's perspective. And that's not lost on superdelegates. One — then-Sen. John Kerry — told the New York Times in 2008 that he feared the repercussions of choosing a nominee that went against the will of the voters.

"My personal opinion is it would be a mistake and disastrous either way for the superdelegates — insiders, establishment politicians — to come along and overturn the expressed view of those pledged delegates," he said.

Indeed, many superdelegates have to be reelected themselves at some point, Ornstein and Mann point out. Going too sharply against voters' wishes isn't going to do them any good in that sense.

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