The constitution says that each state shall determine how its electors are chosen.
As of now, each state chooses its electors based on the popular vote within the state.
So this isn’t really overriding what the constitution says. The legislatures of each state are still deciding how the electors will be chosen.
However, the legality of an interstate agreement on choosing electors is questionable. The courts would get involved if enough states pass this law and want to act on it in a presidential election.
Understanding and interpreting the constitution always comes back to the courts. That’s why elections are important, since the president chooses judges in the lower federal courts and the Supreme Court.
If you get enough liberals in Congress, combined with a liberal president, liberal judges will be appointed who will decide that this scheme is completely legal, even though many of us think it’s not legal to have states agree with other states on how to allocate electoral votes.
You are quite right - Article I section 2 just says the state legislature decides how to choose the electors.
I guess, strictly speaking, the legislature could specify that electors must be members of the Democratic party, for example?
Thank you. It is little known fact that the constitution invests the power to elect the President in the state legislatures. Also the Senators. An amendment changed the election of Senators to a popular vote and just look at what that mistake has caused.