Until recently, it seemed possible, if not likely, that Cruz would keep Trump short of the requisite number of delegates, forcing a scramble for support at an open convention. But a sense of inevitability began to build within the past few weeks for Trump, as he dominated in New York’s primary and then in contests throughout the Northeast.
http://www.realclearpolitics.com/articles/2016/05/04/trump_assumes_gop_mantle_with_indiana_victory_130469.html