It's the last 20% that's the hardest, though (apart from the first 1%). No state with Republican leadership will ever sign it, because they know that they depen

It's the last 20% that's the hardest, though (apart from the first 1%). No state with Republican leadership will ever sign it, because they know that they depend on minority rule. That means that the Democrats effectively have to run enough states to control the Electoral College anyway, and winning enough branches of a state legislature to pass laws is generally more difficult than winning that state in a presidential election. The one thing that's working in favor of the NPVIC happening is that it doesn't have to happen all at once, but that's a double-edged sword - if we get a state or two in the purpleish zone to sign on one year, but it's not enough to get to 270, then they could repeal it the next year. In particular, it'll be really interesting to see what happens if/when we get to the point where any state joining the NPVIC would push it over the edge. Would that state waver knowing that they're going to be the ones to press the big red button? You also have the judiciary to worry about. It's not obvious that the NPVIC is constitutional, and I highly doubt that the current Supreme Court, packed as it is with activist right-wing judges, would let it happen.