You've heard a lot of talk about Superdelegates over the last few weeks. Superdelegates aren't selected based on the primary and caucus votes, like regular delegates. Plus, they get to decide which candidate to support. And just today, one Superdelegate from South Dakota finally announced who she's supporting, while another made a switch. 

Superdelegates aren't based on popular vote and they are seated automatically, based on their status as current or former party leaders and elected officials. 

For example in South Dakota, Democratic Party chair, Jack Billion, former Senator Tom Daschle, Representative Stephanie Herseth Sandlin and Senator Tim Johnson are all Superdelegates. 

South Dakota has seven Superdelegates in all. Six of them had given their support to Obama. Today Cheryl Chapman, Vice Chairman of the state's Democratic Party, announced she will support Hillary Clinton because she won South Dakota. 

And Senator Tim Johnson, who had previously endorsed Obama, said he will support Clinton at the Democratic convention if she is still in the race. He had said he would support the winner of the state's primary. 

South Dakota's other two Superdelegates, Nick Nemec and Sharon Stroschein, are supporting Obama.
Obama has the support of 395 Superdelegates and 2,158 in all. Clinton has 286 Superdelegates and 1,926 delegates total.