Using the 2012 election results and uniform swing, I can show you why republican have a "structural" disadvantage when it comes to winning the electoral college in some cases.
In a tied election, here's how we start out:Democrat: 272Republican: 253Undecided: 13
Virginia is very close in a Florida 2000 fashion, but the democrats still have 272 electoral votes. Republicans would need to win by at least 1.5% (!) to win the electoral college, and successfully get their next state after Virginia, in this case Pennsylvania or Colorado.
Republican Win by 1:Republican: 266Democrat: 272As I've said before, democrats have many more "lean" states than republicans do, and republicans have many more "safe" states than democrats do. I realize that swing states are swing states, but they all lean left to a degree (NH, IA, WI, CO, PA all lean left despite being "toss-ups"). The only swing states in the 2012 election that don't lean democratic are NC, OH, and VA.
Republican Win by 2:
Republican: 303Democrat: 235NH, IA, CO, and PA are all between 1-2 points more D than the country (as of 2012), so republicans see a major improvement from their 1 point win in the electoral college. So the republicans problem only exists when the election has less than a 2% margin of victory for them.
Democrats on the other hand can get their electoral votes quickly with small wins, but slows down once they get comfortable wins, for example:
Democrat Win by 1:Democrat: 303Republican: 235Democrats can get over 300 while winning by 1 point, and yet republicans can win by 1 and lose the electoral college. This is the result of many swing states (NH, IA, CO, PA, NV as I've noted) being only slightly left of the popular vote, s
o the swing states essential for winning a presidential election are slightly more favorable towards democrats, this is the ultimate reason why republicans have a structural disadvantage.
Democrat Win by 10:Democrat: 347Republican: 191Simply because Georgia, Arizona, and all the other Likely R states are so far away from North Carolina PVI wise, democrats winning by 10 only gets them 347 electoral votes. Where a republican would get 360 electoral votes and far more states.
Pat yourself on the back if you read all that. Feel free to make your own maps or explanations for this as well.