businessman donald trump won the 2016 republican primaries, representing a dramatic policy shift from traditional conservatism to an aggressively populist ideology with overtones of cultural identity politics. numerous high-profile republicans, including past presidential nominees like mitt romney, announced their opposition to trump; some even did so after he received the gop nomination. much of the republican opposition to trump stemmed from concerns that his disdain for political correctness, his support from the ethno-nationalist alt-right, his virulent criticism of the mainstream news media, and his expressions of approval for political violence would result in the gop losing the presidential election and lead to significant gop losses in other races. in one of the largest upsets in american political history, trump went on to defeat hillary clinton in the 2016 presidential election.