States wanting to preserve the EC need to pass counter laws stating that their states EC votes always go to who the EC winner would have been if the national popular vote was not a factor used by any other state.
This way even if 270 EC votes can be corralled by the Anti-EC states, it only takes one pro-EC purple state to undo that if their state went for the original EC loser but popular vote winner.
I wonder what would happen if a state passed a law stating that the vote in their state shall be certified only for the purpose of choosing that state's Electoral College delegation, and may not be used for any national purpose.
This would invalidate the counting of that state's so-called popular vote for use outside the state, and render a national popular vote an inaccurate measure for selecting a President.
-PJ