Oh, this can't be right. Non Sequitur told me interstate compacts aren't allowed.
Article I, Section 10, Clause 3: "No State shall, without the Consent of Congress, ...enter into any Agreement or Compact with another State..."
You might want to actually try reading the Constitution sometime. There are no pictures, but I'll be glad to help you with all the big words.
"Any state could become a member of the compact, and any state could withdraw from the group -- except during the final six months of a president's term.
Basically, compacts are OK as long as they don't infringe on federal sovereignty. I can't imagine a bigger infringement on federal sovereignty than attempting to bypass the constitutionally mandated electoral college system. So I'd bet dollars to donuts SCOTUS would strike this down, unless, of course, Congress specifically authorizes it.