Hillary Clinton

As Bernie Sanders and his supporters argue that Hillary Clinton can't clinch the Democratic nomination on Tuesday - because superdelegates don't count until the convention - it is worth noting that Sanders endorsed Barack Obama two days after Obama crossed the magic number (pledged + superdelegate), saying he had become Democratic nominee.

And Sanders' endorsement of Obama came before Clinton had officially exited the 2008 presidential race.

"I plan to play a very active role," Sanders said of endorsing Obama, according to an interview in the June 5, 2008 Burlington Free Press. "I will do everything I can to see that he is elected president."

But the newspaper added, "Sanders said he held off supporting either of the Democrats [Obama or Clinton] because he has made it a custom not to support any Democrat for the presidential nomination until the party had chosen its nominee."