Trump backtracking on his pledge to support the eventual nominee may cost him delegates in South Carolina where he won all 50.
http://time.com/4278295/donald-trump...ina-delegates/
Early appointees to the rules committee lean towards striking down the 8 state threshold for a nominee.
http://www.politico.com/story/2016/0...mp-cruz-221355
Already at least 100 delegates are talking about abandoning Trump after the first ballot, and Cruz is whipping him at getting loyal delegates at state-level conventions.
http://www.politico.com/story/2016/0...cramble-221443
Combine that with polls that don't have Trump doing great anywhere other than NYC, and it looks strongly like Trump limps into the convention with well under a majority, and gets defeated once the ballot opens up.