We're hearing a lot about how costly it would be to alienate Trump supporters. If Trump gets the most delegates, but the nomination is given to somebody else at the convention, we're supposed to believe that such a scenario would be too costly. Trump supporters would leave the party, refuse to vote for the nominee, or whatever.
There are a lot of problems with that kind of reasoning. A big problem is that alienating Trump's opponents would cost even more. There are at least about as many highly committed opponents of Trump as there are highly committed supporters. Most likely, the opponents outnumber the supporters (though a lot of Republicans aren't in either category). We know that Trump supporters are less educated, make less money, and are less active in the party. Who would you rather alienate? The Trump supporters, who are much less a part of the backbone of the party? Or the more educated, wealthier, and more politically active people the party is more dependent upon?
A large group of Republicans will be upset either way. Upsetting the Trump supporters makes more sense. And nominating somebody other than Trump will be better in other ways. It will give us a more electable candidate, will be more beneficial to the party's reputation in the short term and long term, will discourage movements like the Trump movement in the future, will do less damage to other campaigns (e.g., Congressional races), etc.
Trump and his supporters decided to participate in the Republican party and its nominating process, with all of its structures and rules. Part of that Republican system is the option of denying the nomination to a candidate who has the most delegates, but not a majority. Another part of the system is that the rules can be changed along the way, even to the point of denying the nomination to a candidate with a majority of the delegates. As I've said before, Trump ought to be denied the nomination either way, even if he has a delegate majority. I doubt that he'll get a majority, though, and that makes the complaints of his supporters even more hollow. Denying him the nomination when he only gets a minority of delegates before the convention, even if it's the largest minority, isn't a difficult decision. It's easy. Republicans need to start acting like it. Stop wringing your hands, stop being nervous and hesitant, and start treating the Trump movement with the opposition it deserves.