Bill Clinton saying "We're all Eisenhower Republicans here"
Obama claiming he would have been a republican before the conservative revolution
Hillary trying out her fucking GOLDWATER credentials to get elected.
And there's Biden talking fondly of Strom Thurmond (Although at least he didn't try to claim his political legacy)
Who are they trying to appeal to? Anyone who likes Goldwater isn't going to vote for a Democrat, ever, and anyone else who knows who he was would hate it.
Electoral politics starts to make a lot more sense when you get pilled on the fact that half of US voters - including 30-40% of Democrats, as you said - are conservatives. The reason why US politics is so fucked is because TV news has manufactured a ton of conservative consent. Voters know what they're voting for when they elect these right-wing ghouls.
"Joe Biden sucks" and "Joe Biden is to the left of 80% of Americans" are both true statements, and they're not mutually exclusive. Manchin is probably to the left of two-thirds of Americans, too.