Political parties, like all human organizations, are composed of individuals. If you do not like the direction the organization is taking, then work to either change the individuals elected to office or work to change their way of thinking.
If Ronald Reagan had not stayed within the organization and worked to change the Republican Party, 1980 would have seen the re-election of Jimmy Carter with a split in the conservative vote just as 1992 saw the election of Bill Clinton with a split conservative vote.
Bush is NO Ronald Reagan.