National Popular Vote Compact Study
The National Popular Vote Compact is among state legislatures. A legislature that signs onto the Compact agrees that in a presidential election, regardless of the outcome of the election in its state, the legislature will direct that state's electors to vote in the Electoral College according to the results of the national popular vote. The Compact would not go into effect until enough states had signed on to guarantee 270 electoral votes.
For more information on the NPV Study, you can visit the LWVUS site.
Chart summarizing all arguments