I do not see how these states can possibly do that. This is not constitutional! We do not vote for the president directly, we vote for electors who are pledged to vote for our presidential candidates. This is a federal office, like senators and congressional representatives. This is a federal election just like any other.
I remember Florida in the 2000 Election. Magnify this by the NATIONAL Popular Vote, add same day registration, slow mail for absentee ballots and the wait for the various legal challenges. 2020, under their insanity, may be decided by 2026?
On the one hand, the Constitution says that Each State shall appoint, in such Manner as the Legislature thereof may direct, a Number of Electors, equal to the whole Number of Senators and Representatives to which the State may be entitled in the Congress.” On the other, it says that “No State shall, without the Consent of Congress... enter into any Agreement or Compact with another State.”
So take your choice. This might be one the courts have to resolve.
I think there is more than a fair chance Trump will take the popular vote in 2020. Won’t they feel silly then.