wouldn't bet on it

(I) wouldn't bet on it.

 and (I) wouldn't count on it.
Fig. I do not believe that something will happen. (Also with that or some specific happening. See examples.) John: I'll be a vice president in a year or two. Mary: I wouldn't bet on that. John: I'll pick up a turkey on the day before Thanksgiving. Mary: Did you order one ahead of time? John: No. Mary: Then I wouldn't count on it.
See also: bet, on