Deciding how to apportion electors falls squarely within the rights of a state legislature. There's no need for proportion of popular vote to correspond to electoral votes.
What the supreme court has said, is that if any decision is delegated to a vote, then that vote must meet constitutional muster.
Using votes cast in another state to determine the results of what is a state election likely violates rights of voters within that state.
And those rights are not wholely the legislature's to delegate away.
It's essentially extrajudicial gerrymandering.
Separately, and coming from another angle- it likely violates the constitution's guarantee of a republican form of government.
> What the supreme court has said, is that if any decision is delegated to a vote, then that vote must meet constitutional muster.
Anything any government in the US does must meet Constitutional muster. I'd like you to cite the specific decision you think indicates that a decision to assign electors based on the national popular vote would not meet such muster.
> Using votes cast in another state to determine the results of what is a state election likely violates rights of voters within that state.
Based on...what? I mean, except that it has survived so far, I can see an argument to the bare Constitution that giving unequal voting power to different voters within the state, which the two to the statewide winner plus one to the winner in each Congressional district method clearly does, violates the 14th Amendment Equal Protection rights of the voters so disadvantaged. But I don't even see a Constitutional argument, much less actual voting rights precedent, that negatively impacts on NPV.
> It's essentially extrajudicial gerrymandering.
Gerrymandering is drawing legislative districts, which is normally “extrajudicial” (since federal districting is expressly a power of state legislatures, and state-level districting is usually also a power of the state legislature, not the judiciary.) And gerrymandering is often legal and in many cases not even subject to federal review. Rucho v. Common Cause, 588 U.S. ___ (2019).
So saying it's “extradjudicial gerrymandering” is all of false, adding meaningless qualifiers to make it sound significant, and not supporting your argument that it is unconstitutional.
> Separately, and coming from another angle- it likely violates the constitution's guarantee of a republican form of government.
How? Based on what argument and applicable precedent?
What the supreme court has said, is that if any decision is delegated to a vote, then that vote must meet constitutional muster.
Using votes cast in another state to determine the results of what is a state election likely violates rights of voters within that state.
And those rights are not wholely the legislature's to delegate away.
It's essentially extrajudicial gerrymandering.
Separately, and coming from another angle- it likely violates the constitution's guarantee of a republican form of government.