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.”
Obama clinched the Democratic nomination on June 3, 2008.
Clinton did not formally end her presidential campaign until June 7, 2008.
With support from both super and pledged delegates, Clinton is expected to clinch the Democratic nomination during Tuesday's round of nominating contests. Sanders' campaign has continued to argue that superdelegates do not count until the convention and thus Clinton cannot secure the Democratic nomination until then.