This comes from Nate Silver at FiveThirtyEight today:
Mr. Obama led in four separate polls of Virginia on Sunday, three of which represented improvement from the prior polls issued by the same polling firms. Virginia has moved out of the tossup category into a state that leans toward Mr. Obama; he has between a 70 and a 75 percent chance of winning it, according to the forecast model.
That represents a problem for Mr. Romney because Virginia’s 13 electoral votes could potentially substitute for Ohio’s 18 under many electoral configurations. If Mr. Obama were to win Virginia along with Wisconsin, Nevada and either Iowa or New Hampshire, he would have enough electoral votes even if he lost Ohio.
If Virginia and New Hampshire–combining for a total of 17 electoral votes, one short of Ohio’s 18 EVs–look to be falling into Obama’s column early on election night, it’s basically over.