For instance, back in their generation there were limits to how much you could toss around "socialism" and "marxist" when there were actual other countries to point to as counterexamples. Sure there were areas where it played well, but elsewhere you had to use circumlocutions like "slippery slope" or just look like a damn fool. Plus once the Russians launched Sputnik there was a big push for science education, and the the dogs and firehoses against civil rights demonstrators was perfect Soviet-propaganda-fodder for a newly-decolonialized world, so the sheer fact that it made us look bad helped push the federal government to supporting voting rights and desegregation.
Then there's the rise of television advertising in politics (and televangelism), and the fundraising incentives that developed. People were more likely to cough up some dough if you pushed their hot buttons, and conservative direct-mailers like Richard Viguerie had the expertise and resources to do it. They were intended to be divisive because the intent was to break up the New Deal coalition.
Pile on top of that wealthy interests and corporations following the strategies of the Powell Memo, investing in think tanks and media resources to provide a more Washington-friendly intellectual/technocratic veneer to conservative policies, thickening the fogbank
And that's just some of it.