Actually, it is covered under Article II, Section I of the Constitution - and states are allowed to choose their electors in any manner they please ...
“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: but no Senator or Representative, or Person holding an Office of Trust or Profit under the United States, shall be appointed an Elector.”
This is DANGEROUS !!! I live in MD and they have already passed this bill. If enough states [totalling 270 electoral votes] pass this legislation, the MD law becomes active. It works like this:
No matter who wins in the state of MD, all of its electoral votes will be cast for the winner of the National Popular Vote [NPV]. So, if the GOP wins MD [not damn likely], MD’s votes would go to the DEM [if he wins the NPV].
This will lead to major campaigning in ONLY the states with the biggest populations: CA, FL, MA, MI, NY, IL, IN, OH, PA, TX, etc.
That is a broad statement and very problematic in this regard. But, I don’t know how this could be described as anything other than a compact. The law is clear and has been upheld by SCOTUS in at least two key decisions, compacts MUST be approved by Congress.
My Govenor Schwanegger (Ca) vetoed this bill so Calif is not a part of this at this time although the legislature which is controlled by the Democrts and if Jerry brown wins
election this fall I suspect this bill will come back and he will sign it. I checked Illinois and Blagovich did sign it into law I suspect anywhere there is a Democrat Govenor this law will be enacted in that state
OTOH, it may set a precident, whereby the People require thier "representatives" to actually cast their votes as directed by those same PEOPLE. Yeah, I know: fat chance.
You are correct that a state can choose its OWN method of selecting electors.
However, the COMPACT that says that the state's method is contingent on other states in the COMPACT also agreeing to abide by the rules constitutes a compact among states that is in violation of Article I Section 10.
States can act individually. They cannot gang up on other states.
-PJ
To turn your example upside down, it is mostly leftist states passing this, so if Maryland votes for the DEM, while the popular vote goes to the GOP, you know the very same leftists in Maryland will throw a hissy fit about having to cast their votes for the GOP candidate.