Mitt Romney wins the popular vote (RCP has him up 1.3 as of now) and loses the electoral vote, OR neither candidate achieves the necessary 270 electoral votes needed to win? Here's the electoral college right now, according primarily to RCP, with "undecided" states (56) being within 1 - 2 points: 2012 Presidential Election Interactive Map and History of the Electoral College
Going by this, which seems like an accurate assessment based on history, as of right now it's Obama- 247 to Romney- 235. This means that, assuming there are no faithless electors, Obama would need 22 of 56 available electoral votes. This is only possible if Obama ONLY wins Ohio (18) + New Hampshire (4), OR if Obama wins ONLY Virginia (13) + Colorado (9). Ohio, Virginia, and NH have Obama +1 or less, Colorado is +1 for Romney. Of those remaining, Nevada and Iowa also lean Obama at around +1, 2ish.
So which is more likely, in your humble opinion?