Mr. Obama’s projected three-point lead in Ohio is important for the following reason, however: it’s slightly larger than the 2.4-point advantage that the model now gives Mr. Obama in the national popular vote.

In other words, based on the data so far this year, Ohio has been slightly Democratic-leaning relative to the country as a whole. That reflects a reversal from the usual circumstances. Normally, Ohio — though very close to the national averages — leans Republican by two points or so…

If Mr. Obama won all the states that John Kerry did in 2004, and Ohio, he would have 264 electoral votes…

However, if Mr. Obama claimed any other competitive state that Mr. Kerry lost — Nevada, Iowa, Virginia, Florida or Colorado, for example — he would win the Electoral College outright, regardless of what happened in New Mexico.