Neal Gabler thinks modern Democrats are a bunch of milksops:
In the days of FDR, the Democratic Party, despite its factions and disagreements, coalesced around one overriding tenet: muscular government action, especially in behalf of the powerless....Belief in the efficacy of government was a prerequisite to gaining the nomination. Democratic aspirants didn't lurch rightward or pray for common ground. They stood and fell on principle. But that was then. The fact is that nowadays you don't get the Democratic presidential nomination unless you are willing to soft-pedal activist liberalism.
OK, but why have Democrats become such wimps?
Sometime in the 1970s, the Democratic Party became basically an "interests" party. It stopped pressing government action as an overriding binding principle and began instead to appeal to individual interest groups: African Americans, Hispanics, women, labor, gays, youth and even Blue Dogs. Anyone who hopes to make headway in the nominating process has to find a way to appeal to many if not all of them. Still, most of these are situated at the left of the political spectrum. Prospective nominees must also appeal to elected Democrats, party officials and, perhaps most of all, those realists who, remembering McGovern's quixotic anti-Vietnam debacle, want desperately to win and believe that only a centrist can do so. This compels aspirants both to placate and temporize.
But this is only half the story. If power in the Democratic party fragmented and then flowed to individual interest groups dedicated to social issues in the 70s, it must have flowed away from a big, well-organized interest group devoted to government action as a way of comprehensively helping the poor and the working class. I wonder which interest group this could be?