The National Popular Vote Interstate Compact

[Virginiá]

"Representing a minority of the population"?  If this were to actually pass in enough states to reach 270, it would presumably be in states representing a majority of the population.  I don't see a realistic combination of remaining states that would be otherwise.

Here is a viable map that consists of the following:

1. States that already have the compact passed
2. States that have an initiative process where voters could get it done themselves
3. States that have a Democrat-controlled legislature that could either pass it or put an amendment on the ballot for this

* There are even more conservative states that allow various forms of initiatives, but I didn't include them (ex: MS/ID/OK/NE). Some of the more conservative states may have difficult regulations for ballot measures.

Also worth noting is that any initiatives passed in GOP-controlled states would probably find themselves at risk when the Republican legislature inevitably puts an amendment on the ballot every 2 years to repeal it.

I'm not saying that map above would be possible in the end, but between Democratic states, states that have already done this and states with initiatives, you could make it work without Republican lawmaker support.

I think there it might be kind of hard to fight a proposal that simply amounts to whoever gets the most votes wins. However, I'm sure Republicans would think of some way to get lots of people to vote against it. Overall I doubt it could be done if the GOP fights it tooth and nail every step of the way with basically unlimited financial support.

[Virginiá]

In a state referendum in a swing state like Florida, any chance that you'd have a decent amount of opposition not from partisan Republicans, but from folks who just don't want the state to give up its special status as a swing state?  I mean, if NPV passes, then the bargaining power of voters in swing states is no greater than that of the voters anywhere else.

Yes, that argument has potential. Though maybe one could argue that because Florida is a large state, it will still hold significance as candidates will want to mine it for votes. Personally I think opposition to a NPVIC initiative automatically starts out a disadvantage but I definitely think it could be defeated. Decent eection reforms that you would think would be easily approved have often been rejected by voters:

Missouri - Early voting amendment (2014) - NO  (landslide rejection)
Connecticut - Early voting amendment (2014) - NO
Ohio - Redistricting reform (2012) - NO

And so on.

[Virginiá]

I wonder how long it would take for lawmakers to start trying to undermine the NPVIC if it ever went into effect. Doing this on a state-by-state basis is probably the worst way to go about it, seeing as America has a long, storied tradition of lawmakers abusing their power over elections to develop advantages for themselves or outright rig the entire process. I think there is at best a 1% chance that lawmakers don't try to repeal this if their party loses due to it. Although given that they control more states and over the past 10-15 years, developed a very troubling record of anti-democratic behavior, and that they depend on the electoral college right now, and that they are more aggressive in undermining or outright repealing citizen-approved laws, I think Republicans would probably be the first to flip out.