With the Iowa caucus a near tie between the two leading Democrats, and with a win in New Hampshire for Bernie Sanders, how is it that Hillary Clinton has 394 delegates and Bernie only has 42? Superdelegates.
In the Democratic Party, there are delegates whose vote isn't determined by the voters in their state. They are free to support any candidate they choose. There are 4,051 regular delegates and 721 superdelegates (for the Democrats) so Hillary's current lead does not guarantee her a win.
The superdelegates are made up of Democrats currently in office as the Congressional Representatives, Senators, or Governors of their state plus some people who are considered party leaders. The idea behind having them is to prevent the nomination of an unelectable candidate.
(I'm sure there's a reason for them besides the Democratic Party thinking its voters are too stupid to be trusted, but I can't think of what it could be. The Republican counterpart of the superdelegates are required to vote the way the voters in the state did in their primary.)
The people in power, and those close to them, want to keep things the way they are and their choice right now is Hillary. They could change their support if they see enough of the popular vote going to Bernie. (Even if they want Hillary, they're not going to commit political suicide for her.)