Hatred of liberals is glue that holds the right together. Not liberalism. It's OK to hold liberal views if prefaced by hatred of liberals.
— Bruce Bartlett (@BruceBartlett) August 14, 2016
In a way Democrats have understood this over the years, but in a way they haven't. Most of them got pretty good at doing the "I'm not like those OTHER liberals, in fact not a liberal at all..." schtick which is about showing tribal allegiance to hating liberals, not about any actual policy (aside from some proof you're willing to STICK IT TO THE LIBERALS stuff like anti-flag burning laws, but those types of things were more about proving your tribal affiliation than they were about the actual policy). That was sometimes good enough for a Senate candidate to trip over the 50% line in a red state and win an election, though since liberals=Democrats to the people they were trying to cater to, the fact that half the Democratic party was always running against the Democratic party didn't do much for brand D generally.
But the part they missed was that some liberal policies would actually be pretty popular. For example, the fact that older people vote leads to some rather obvious liberal policies to support, especially in states with lots of older people. Even George Bush was smart enough to support a Medicare expansion. If they could have wedded popular liberal policies with the "I hate liberals, too" schtick, then they might have had a winning formula, at least individually. Instead it too often just had them run up against the basic "give the people a choice between a Republican and a Republican..." problem.