I think this plot might pass muster constitutionally. But Ohio and other swing states would have to sign on. Why would they do that? In any event the popular vote tends to track the electoral vote quite well. The nightmare would be if there were say 50,000 or less votes separately the candidates. Then every vote in the land would be hand counted, and litigated. This hand counting of ballots is quite insane. Close is good enough.
I think this plot might pass muster constitutionally. But Ohio and other swing states would have to sign on. I just did some more thinking. Suppose Mr. Popular wins the national popular vote, but Mr. California wins the California vote. The intention of this legislation is that Mr. Popular should win the national election, and thus it would seem that California should want to cast its electors for Mr. Popular regardless of how many or how few states adopt similar policies.
Why, then, cast things in terms of a "pact" which must be signed onto by enough states to swing the election before taking effect?