Watch: Bernie Sanders Admits Some Supporters Won't Vote Clinton

Bernie Sanders says vote Hillary Clinton
Former Democratic presidential candidate Bernie Sanders speaks during a rally in the Manhattan borough of New York on June 23. Sanders has urged his supporters to back Hillary Clinton. Lucas Jackson/Reuters

Bernie Sanders has urged his supporters to back Hillary Clinton over Donald Trump for the U.S. Presidency—but admitted that some of them may still not do so.

Speaking to Face the Nation on CBS News, Sanders, who made an unsuccessful bid for the Democratic presidential nomination to the left of Clinton, said: "We have over 13 million people who supported my candidacy, and I have no doubt that there are some of those people who will not vote for Hillary Clinton."

He said that his supporters should avoid the "personality conflicts that the media tries to bring forward and focus on the real issues impacting the American people."

"When you do that," he said, "I think the choice is pretty clear. And that is that Hillary Clinton is far and away the superior candidate."

And he insisted that "I would say that the vast majority of them…will come on board Secretary Clinton's campaign."