Superdelegates are otherwise known as "unpledged delegates," who are usually governors, congressmen and state party leaders. They can "pledge" their support to candidates, but are not bound to vote that way like normal delegates are -- meaning they can change their mind until the party's nominating convention.
By contrast, Sanders holds only ten superdelegates -- and that has motivated some supporters to take action.
Sanders supporters launched two online petitions to appeal to the superdelegates, asking them to support the candidate who wins the popular vote in their state. By Monday afternoon, one petition had 118,151 signatures. The other, which implored superdelegates to "align yourself with regular voters - not party elites," had 173,769.
The tides did turn in 2008 when many superdelegates, seeing that Barack Obama was surpassing Clinton in overall support, switched teams and backed the then-senator from Illinois.
In Nevada, which holds its Democratic presidential caucus on Feb. 20, Clinton has received pledges from Rep. Dina Titus, State Sen. Ruben Kihuen, Democratic National Committee Hispanic caucus vice chair Andres Ramirez.
National committeewoman Erin Bilbray is Sanders' lone pledged delegate in that state. Sen. Harry Reid, state party chair Roberta Lange, state party first vice chair Chris Wicker and DNC at-large member Artie Blanco are all neutral.
In South Carolina, where the Democratic primary occurs Feb. 27, Rep. James Clyburn, state party chair Jamie Harrison and State Rep. Gilda Cobb-Hunter are also presently neutral. Sanders has no pledged delegates in the Palmetto State, unlike Clinton -- who has won over state party first vice chair Kaye Koonce, national committeeman Boyd Brown and DNC at-large member Donald Fowler.