The Democrats have voted like a cohesive group in the past. Examples:
2020 democrats 94-5 for Biden, republicans 94-6 for Trump
2016 democrats 89-8 for Clinton, republican 88-8 for Trump
2012 democrats 92-6 for Obama, republicans 93-5 for Romney
2008 democrats 89-10 for Obama, republicans 90-9 McCain
2004 democrats 89-11 for Kerry, republicans 93-6 for Bush
2000 democrats 87-11 for Gore, republicans 91-8 for Bush
I’ll stop there as 1992/96 with Perot in the race threw the stats off. Presidential wise, cohesion is relatively even. There is a 4-point difference in 2000/04, the GOP achieved 90% of their base vote in all the above except for 2016. The democrats achieved this only twice. There’s not much difference in the voting habits of those who identify with either party. Now in-fighting among the party faithful could be quite different. But not voting habits.
The thing is independents made the difference in who won or lost. You’re correct, independents are not one huge ideological block. They’re all over the place. I doubt one could ever organize them into an organized voting black as Republicans and Democrats can. Independents can swing wildly from one election to the next. You seen this in Virginia’s governor race. Biden won Virginia independents by 19 points in 2020, 57-38, but McAuliffe lost them to Youngkin by 9 points, 54-45. A 28-point swing.
Perhaps one of the biggest swings without research further back than 2000 was independents voting for Democratic congressional candidates 58-39 in 2006 and then voting for Republican congressional candidates 57-36 in 2010. That’s a 38-point swing. From a plus 19 to a minus 19 for the Democrats.
The midterm voting by party also shows the same cohesion as the presidential.
