That is kind of the point though: Splitting it by CD would give candidates a reason to go to places like Northern CA and Upstate NY that are currently almost, if not completely, irrelevant in those states. If you win NYC, you won NY; every single northern and western NY voter combined cannot offset the 20 million people who live in metro-NYC (though many of those are registered to vote in NJ, PA or CT.) Win L.A., San Diego, 'Frisco and Sacramento and you have won CA, and only one of those has even a remote chance of going GOP.

It would be a more fair system, but screw the Dems hard (note that the latter does not diminish the justice of the former.)

Let us be brutally honest: There are 21 states with 10+ electoral votes; Republicans have NO shot in 13 of them, and 3 others have not gone Republican since '04. There are 6 states with 20+ electoral votes; Republicans only get 1 consistently, and 3 others have not gone Republican since '88. The biggest state, and 4 of the top 6 (IL and PA are tied for 5th,) are solidly Dem. Of the top 10, Republicans just lost 8. As long as it is winner take all, the "demographic destiny" of the increasingly urban US will doom the GOP, ideologically if not electorally. Dominating a state with Houston, Dallas AND San Antone is the mother of all aberrations, only possible because TX is SO big. But it cannot last; FL is leaving the fold, and when TX follows the winner-take-all system will leave the GOP NOTHING.

Now imagine a world where Miami-Dade only gave Dems 4 EVs instead of 29. Where Northern CA gave Romney 20, and non-Chicago IL gave him 10. Going by congressional district would not only be more fair (though I agree with Isaac about the need for non-partisan automated redistricting,) it is the GOPs sole hope.