I'm shocked at what some people are labeling as a Romney "landslide". I consider a landslide whenever a losing presidential candidate gets less than 100 electoral votes. I have seen no signs that this election will be a landslide for either side, but under that definition, the following are possible Romney landslides:
1.
Romney 448
Obama 90
2.
Romney 474
Obama 64
3.
Romney 447
Obama 91
4. This one isn't necessarily a landslide, but it's the widest EC margin that Romney can realistically win by (though it's still unlikely):
Romney 374
Obama 164
Note that I left Hawaii and the District for Columbia for Obama on all these maps. That's because DC has always voted for the Democratic candidate for president, and Hawaii has always done hee same whenever the Dems get more than one state (and Obama probably will, even in a Romney landslide).