If you don't get the majority of the electoral votes (270 currently) then it falls to the house of representatives to vote for the president and unlike states which have defined boundaries, congressional district boundaries are subject to possible change under the US census every 10 years of which gerrymandering can occur! 

Actually after having giving some thoughts, it's not such a bad idea afterall that congressional districts can get gerrymandered if it means that democrats are willing to give a shit about state level elections in the end ... 

The power of the states altogether is far greater than the power of a federal district (DC) ... 

I still think distribution based on percentage is better than winner take all