Immigration is part of the justification of America.
If it doesn't permit immigration, why is anyone in the United States at all aside from its native population? Without the view that immigration is benign, the US is territory stolen from the tribespeople which lived in the country to begin with. It loses its legitimacy.
So there's a choice. Immigration (not slavery, which came later) is either America's original sin, or its justifying virtue. {or both but that's complicated}.
If you are against it, it's a sin. If you are for it, it is a virtue.
It seems fitting that immigration looks like it will end the claims of white nationalists (not all white people but too many) to the country. They seem to think immigration is a bad idea. So their existence in the US itself is a matter of shame - by their own reasoning.
It will be nice to see this GOP, which represents their views, lose its relevance; because once it's gone, there's no way back.
I say this as someone who rejects the vogue for attacks on white people generally and on American history as entirely an exercise in racism (although of course it has its incidents, and maladies that have required, and still reqiure, curing).
But the GOP has come to express an abhorrent view of whiteness as an exclusive thing to cling to. And so it has set aside the justification for America's existence from its inception. It needs to go.