It's called the "National Popular Vote Interstate Compact". The Interstate Compact part just means that it's a legally binding agreement between states.
It would be implementing a popular vote nationwide by circumventing the electoral college. It’s just a mechanism to get around modifying the constitution.
The current compact only kicks in is the electoral college vote and the popular vote differ.
That is quite a bit different than the popular vote as you can see this year when Trump would have basically run the board of electoral college votes without that caveat.
Either way, the person who wins the popular vote wins the election; what difference does it make how many electoral college votes they get (if the electoral votes are determined by a rule like that).
The National Popular Vote Interstate Compact is a way to choose the president by popular vote without the overhead of removing the electoral college.
https://en.wikipedia.org/wiki/National_Popular_Vote_Intersta...