In my unlawyerly opinion, this violates the Constitutional guarantee to the States of a Republican government. Other States and other voters are determining who gets the EC votes from the State in question.
Probably so ... however, it is explicitly Constitutional, according to Article 2, Section 1:
Each State shall appoint, in such Manner as the Legislature thereof may direct, a Number of Electors....
That they're "directing" themselves into meaninglessness is beside the point -- they're acting within the bounds of the Constitution.
Exactly.
And here's my scenario,
The close loser in one State will sue, get the election in another State recounted numerous times.
No State in the pact will be able to cast their electoral votes until that or many States reconcile their vote count.
Imagine if the Presidential election was undetermined by what is happening in Minnesota.
They really haven't thought this through.
It could take years to elect a president.