What are democratic superdelegates? when and why was the role created?

At the Democratic national convention in July, 719 people will cast votes for Hillary Clinton or Bernie Sanders to be the presidential nomination who were not selected at any primary or caucus.

These are the so-called superdelegates, but it is not their role at the convention, nor any special powers or abilities, that makes them super. It is their stupendous ability to attract controversy.

There are three ways to become a super delegate. The first is to be elected to public office as a Democratic governor, senator or congressman. The second is to become one of 438 members of the Democratic National Committee as a loyal party activist or power broker. The third and most difficult is to become a super delegate for life by having served as president, vice-president, DNC chair or Democratic leader in either chamber of the US Congress.

the term is einsatzgruppen