Nope,not at all. If the nominee with the most delegates doesn’t cross the threshold then the delegates are free to support whoever they choose (some staten laws may prevent this but mostly, this is the case). That’s what Bush is hoping for and explains why so many people are still in the race. They don’t need to win, they just need to make sure Trump or Cruz don’t have enough delegates to pass that threshold.
That’s where I get confused. I mean, if you cant gt the majority of your own party to vote for you in the primary,what makes you think you have any chance in the general?