Beverly Mann — Clinton’s figured out how to ensure her victory: Threaten Sanders that if he doesn’t endorse her, pronto, she’ll begin campaigning as a triangular.
Depends on who has leverage on this issue. If Clinton triangulates like Bill, she risks losing so much of the progressive base that she can't win a general election. The first rule is to secure one's base. HRC has not done that and, in fact, has alienated a good part of it. I'm not sure that Bernie endorsing HRC would fix that. At least some of the progressive base would likely see that as a betrayal.