If MA wants to assign their electors according to the popular vote, then fine. How many do they get? Twelve?
This is the way it works in MD [it passed same law]. The law is inoperative until enough states representing 270 electoral votes pass the same law.
If that happens, in the following presidential election, then the electoral votes representing MD [10] are awarded to the winner of the national popular vote - regardless of who won the state.
So, the net effect is to take the states with the smallest populations out of the game. AK, HI, ID, ME, MT, ND, SD, UT, VT, WY, etc. become highly irrelevent.
CA, FL, IL, IN, MA, MI, NJ, NY, PA, TX, etc. become the kingmakers.
Conceivably [if all states passed this law], the winner of the popular vote would receive ALL of the electoral votes [538] - even if he won the popular vote by one vote.
I don't know about you, but I want my vote represented. If I vote in my state, and my candidate wins [but loses the popular vote] - I want my state's electoral votes counted for my guy.
The smaller states should be screaming bloody murder and filing lawsuits.