Biden has canceled ad spending in Nevada:
Well, that is interesting... The question is why?
a) They are out of money/need money for IA/NH/SC more
b) They think they have it locked up
c) They think they can't win it
Which of those is the case?
I guess that he's trying to go all-in on IA/NH so that a strong finish would give him enough momentum for an outright win in NV and a landslide in SC going into Super Tuesday. It's still a puzzling decision, though, as NV is a state that he could quickly lose ground to Sanders if he's not careful (unlike say SC where he pulled out earlier this month which is already a foregone conclusion).
That might be too charitable for an explanation, though, as it's also possible that his campaign's finances are not in the best shape compared to the other candidates.