House GOP members are now farther to the right of the political spectrum as measured by the DW Nominate scale than the House Republican caucus of 1967. There is almost no overlap as shown in this histogram posted at
Daily Kos. They are endangering their relevance with political extremists who see any compromise--once considered the art of politics--with the other party as treasonous.
It is a process that began with the 'Newt Gingrich revolution' of 1994 that wiped out conservative southern Democrats who provided a significant ideological overlap between Democrat and Republican. Today there is no overlap, only a gap, between the two parties in the House.