Narrator: Civil rights was about to tear the country, and the Democratic Party, apart. Many Democrats in the South were committed to segregation. As they saw their party support integration, they began to seek refuge in the Republican Party. 
Herbert Parmet, biographer: Poor white workers in Texas and elsewhere felt there was a threat, of all these hordes of blacks becoming unleashed and competing with them for status and jobs. And so you have the mass turnover to Republican Party in the South, state after state. ...
Richard Viguerie, conservative activist: And they become the nucleus of the new Republican Party, not only in Texas but across the country. And this was the beginning of the conservative movement, and to this day it serves as the base of the Republican Party. 

http://www.pbs.org/wgbh/americanexperience/films/bush/