Of course they will try to do this. The states with no voter ID want to rule over all of us.
Everything I read about the CIA is that it is anti-US which makes me wonder if that agency should be shut off.
1) In a very close election, lawsuits could challenge election results anywhere in the country in any precinct. This would delay the electoral votes of every state in the compact, basically creating chaos.
2) Any type of regional natural disaster or hardship (floods, earthquake, blizzard, wildfires, etc) that serve to diminish turnout, could be used to say that voters in one region were underrepresented, and justify sending the vote to the House who would likely just follow party lines.
3) Any type of national popular vote would bring into play national election standards set by law for federal offices. Such laws could be manipulated by a party in power to favor its electoral advantage nationwide.