In his book "Why the Electoral College is Bad for America," George Edwards reports that six times in American history a switch of less than 10,000 votes would have made the popular vote runner-up the president, in addition to the other occasions where that did happen.
As Alexander Keyssar, the preeminent historian of the vote in American, put it in a review of the book, the most "unpopular political institution" in America is the electoral college.
Any politician supporting reform of the presidential selection system to make it more directly based on the national popular vote will be pushing something popular.