Why Can’t the G.O.P. Stop Trump?
If Republican Party leaders dislike Donald J. Trump so much, why haven’t they done more to stop him?
They should be able to. In “The Party Decides,” a book I wrote in 2008 with Marty Cohen, David Karol and John Zaller, we argued that the leaders of party coalitions have great influence over the selection of a presidential nominee.
http://www.nytimes.com/2016/03/01/opinion/campaign-stops/why-cant-the-gop-stop-trump.html