The scheme of allocating EVs based on the popular vote nationally will never survive its first court test.
The moment a state won by a Republican allocates its EVs to a Democrat who won the popular vote, any Republican voter in the state can file a suit under "the equal protection clause" -- challenging the state's decision as running contrary to the expressed wishes of the majority of its voters.
And they will win. Even in the 9th Circuit...
There is only a little over a month between the popular vote and the deadline to determine who the people are who will cast the electoral votes. It may be impossible to sort it all out in time with the Democrats creating chaos (if that helps them). In 2000 it was just one state—it could be a lot of states if they try to implement this plan. They have most of the lawyers.
The Founding Fathers in the Constitution did not require states to allow their citizens to vote for president, much less award all their electoral votes based upon the vote of their citizens.
In 1789, in the nation’s first election, the people had no vote for President in most states, only men who owned a substantial amount of property could vote, and only three states used the state-by-state winner-take-all method to award electoral votes.
The Equal Protection Clause of the 14th Amendment says:
“no state [shall] deny to any person within its jurisdiction the equal protection of the laws” No state would deny equal protection of the laws to any person within its jurisdiction as a result of electing its presidential electors in accordance with the National Popular Vote compact. The National Popular Vote bill does not violate the Equal Protection Clause of the 14th Amendment.