The U.S. Supreme Court has just recently refused to hear a lawsuit challenging the constitutionality of the current "winner-take-all" method of awarding electoral votes.
Winner-take-all laws give all of a state's electoral votes to the presidential candidate who gets the most popular votes inside each separate state. The lawsuit was initiated by Harvard Law Professor Larry Lessig and his Equal Citizens group. The lawsuit was an attempt to reform the method of electing the President by judicial action. The lawsuit argued that winner-take-all disenfranchises all the voters who didn't support the leading candidate in their particular state.
CNN story
Now that the judicial route has been foreclosed, the only realistic way to get a national popular vote for President is through state legislative action. That is why National Popular Vote has worked tirelessly since 2006 to advance the National Popular Vote Compact in state legislatures across the country.
The U.S. Supreme Court has repeatedly ruled that states have exclusive and complete power over their own electors. As far back as 1892 in McPherson v. Blacker the Court ruled that the states determine how we elect the President. The Court said “...the appointment and mode of appointment of electors belong exclusively to the states under the constitution of the United States."
So far, 15 states plus the District of Columbia have enacted the National Popular Vote Compact into law. Together these states have 195 electoral votes. The Compact will take effect when passed by states with 270 electoral votes. There are a total of 538 electoral votes, so there are 343 possible additional electoral votes. We need states with just 75 electoral votes to put the Compact into effect.