States are not sovereign. Even before the Civil War the notion of State sovereignty was long settled, but certainly after the war the issue was dead.
Regardless, as I have pointed out so many times I no longer know in which threads, the EC's mandate has long been circumvented by the States such that it no longer exists (and it had little to nothing to do with State sovereignty to begin with and everything to do with protecting slavery). The majority of the States have castrated the notion of "faithless" electors, requiring instead that their electors act as rubber stamps for the popular vote winner.
Iow, the popular vote is the only vote that exists. There is no other vote other than as a meaningless theatre.
So we are left with a vestigial arm long since cut off that serves absolutely no purpose, other than to unjustifiably weight my vote to equal 10,000 of your vote, just because you live five feet away from me. In effect.
It is a national office and it should be decided by a national vote. Period. Just flip it and consider the outrage if State elections were all determined by a national vote. The outrage would never end.
No state has magical powers that transform its inhabitants into different classes of American votes, yet that is precisely what the EC does, only without merit. It doesn't matter what anyone wishes to argue in favor of the EC, it is objectively, conclusively and irrefutably non-existent in all substantive forms and serves no justifiable purpose.
The only reasons it still exists are (1) it takes too much effort to get rid of it and (2) it allows for election fraud, which is all Republicans have left to them, since they cannot win on merit.