Welcome to DU!The truly grassroots left-of-center political community where regular people, not algorithms, drive the discussions and set the standards.Join the community:Create a free accountSupport DU (and get rid of ads!):Become a Star Member
He's deliberately held back because he doesn't want to give the Republicans ammunition to use against her if she is the nominee. Hillary has no such scruples because a) she regards herself as inevitable, so why bother?; and b) she'd rather see President Trump than President Sanders if she were to lose the nomination.