OK this is a bit of a tangent, forgive me:
One thing I find bothersome about the “Democrats importing people to win elections” narrative – setting aside the fact that immigrants primarily settle in Democratic strongholds as it is – is that it sort of assumes that being against whatever new people show up is a terminal value of the Republicans, which is silly. The American right does pretty well with people who emigrated from the Communist bloc, for instance, but it’s not that those people are inherently more “right-wing” in an objective sense, it’s that the American right has defined itself in a way that offers them more. It could easily do the same for later waves of immigrants, if only it could wrestle down the xenophobic portion of its base. They fucked it up about as hard as possible, but that GOP postmortem that determined they needed to win over Hispanic voters and were in a position to do so was correct – ICE can’t kick down enough doors to reverse that demographic trend.
There’s a common reactionary concern that the influx will fundamentally reshape the culture of America, but I’m pretty skeptical. America has had comparable waves of immigration in the past, and they did have some effect, but that effect is generally considered positive or neutral now, and none of them did nearly as much to change the nature of the country as WW2. Over the kind of timeframe where demographic shifts become an issue, most of the current batch of migrants will assimilate and shift rightward, and if the world hasn’t blown up by then, in a hundred years people will be pointing to them as examples of the “good” kind of immigrant to contrast with the hordes of unamerican degenerates pouring in from, I dunno, let’s say Aragon.
The uniting factor that makes immigrants more likely to vote Democrat is that the Democrats have less of an active interest in screwing them, and the Republicans are only interested in screwing them because they’re them, so it’s really a self-inflicted wound. Even the much-feared Radical Islamists are closest ideologically and politically to hard-line localist fundamentalist types who are die-hard Republican voters.
I don’t know enough about the history to say whether the Democrats actually were the ones who made xenophobia vs. xenophilia into a party-lines issue, but it’s definitely the Republicans who kept it there, and that tactic had at least as much effect on the resulting consequences as the original immigration reforms and the civil rights movement.