@Hauta
actually, if you look at the Democrats in congress from the late 1950s to mid 1970s: you see a LOT of the same faces. check it out online, 85th congress to the 93rd. the change happened less due to ideology switches, rather natural changing of guard within party. most new democrats who came in, actually had always been registered as Democrat.
there's this idea of the "New left" and "New right" that isn't quite accurate when you have deep retrospection
As far as demographic shifts in voting, the Republican/Progressive split really hurt mainstream Republicans with the black vote, and the FDR era was really when Democrats began securing the black vote: yes, even racist democrats in the south, who still kept Jim Crow alive. this is mostly due to the pro-welfare left, and the economically disadvantaged black population.
meanwhile the christian voting base had its major shift during Reagan, years after the supposed "New Right" and "New Left"
what ACTUALLY happened was the Democrats didn't wake up and say "hey let's not be racist" rather they changed tactics, to an anti-racist party. same politicians, new strategy.
and then you get a generation of kids growing up, where Democrats failed with Carter, and as Reagan swept up many states, we begin to see the states change loyalties primarily due to massive urbanization during the population booms of the time. thus the red racist south was born, in the minds of much of the new generation.
during the late 80s-90s era, the youth who had grown up under the new strategy (who ACTUALLY believe racism was bad) came to the forefront and fought until securing the Clinton presidency. This was at a time when the Libertarian party had been MUCH more fringe, and up until that point, we hadn't seen any big-government conservatives (like HW Bush), so the fringe libertarians really hurt the "conservative" name with the militant religious, anti-gay, anti-atheist, anti-evolution, and even still, heavily racist and sexist ranks.
Clinton was a significant turning point for when the Right looked to Bush, but then as the Iraq war set in, sure small government conservatives AND anti-war liberals helped spearhead much of the vietnam-era libertarianism that is no coming back again today.
meanwhile the fringe right had metastasized into the mainstream Republican party.
democrats looked around, and thought that the best way to win was to appeal to the abused minorities, despite a legitimate venue for that platform being less prevalent carrying into the 21st century.
now we're here, with a rise of socialism in the far left, and the mainstream democrats look more for the minority vote, as the Republicans bend over for anyone they can get a vote off of, splitting their party between true conservatives and the previous neocons. Libertarians find themselves much more in the middle, and attracting a growing center feeling demonized by each side in elections prior.