Bernie again pledged to help the nominee of the Democratic Party win the White House whether that person is Hillary or him:
Bernie Sanders told MSNBC yesterday, "I will do everything that I can, and I think Hillary Clinton and I agree on this, that we will do everything we can to make sure that a Republican does not win the White House. I will knock my brains out, I will work seven days a week to make sure that that does not happen if I am the nominee and if I am not the nominee. That's what I will do."
Maddow Blog
This has long been his position.
Individual Bernie supporters must make up their own minds if Bernie is not nominated, and I’m not going to tell you what to do. But I bring you Bernie’s view for your consideration.