GOP adopted a popular election system parallel to Dems. Goldwater conquered the party through grassroots organizing and the traditional method of winning states. Once he won California he clinched the nomination, with an uncertain contested convention best outcome Rocky could hope for before that. Eastern networks had atrophied entirely by 1964, as Rocky said "You're looking at it" (Eastern Establishment) privately.
Political machines in places like Philadelphia (collapsed in the late 40's/early 50's), papers like the New York Herald-Tribune (folded in 62 I believe) and of course numerous politicians in places like New York, New England and so on.
The Conservatives had the upper had within the party since the Bullmoose Party, and post New Deal a lot of the politicians in the Eastern Establishment were having a hard time competing and maintaining power with the increase in union strength and democratic voting, in their former bastion.
The Conservatives on the other hand were plowing fertile fields in the Sunbelt in places like Arizona, Southern California, and metros throughout the South (Dallas, Atlanta, Tampa, Charlotte).
