I will do this analysis using the following criteria
1. Obama won 365 EVs last cycle. This time those states have 359 EVS. From that I subtract the 2nd CD in NE and IN (each of which Nate has % of Obama winning <15) for a base of 347.
2. There are 9 states considered battlegrounds, containing 110 electoral votes: FL (29), OH (18), NC (15), VA (13), WI (10), CO (9), NV (6), IA (6), NH (4). For Romney to win outright he needs 79 electoral votes, for a 269-269 tie and sending it to the house he needs 78.
Starting with states 85% or more likely for Obama
NH 4 86%
NV 6 86%
WI 10 85% Total of 20 EVs, leaving 90 up for grabs
States at 77%
VA 13 77% 20 +13 =33 EVS, leaving 77 EVs, and election would be over
States at 76%
CO 9 76%
IA 6 76% 33 + 15 = 48 EVs, leaving 62 EVs
State at 75%
OH 18 75% 48 + 18 = 66 EVs, leaving 44 EVs
At this point, without Florida, which Nate as at 67% for Obama, the electoral vote would be Obama 303 Romney 235
Throw in Florida and it would be 332-206.
That would leave NC as only one of competitive states Romney would carry.
But Romney now has to defend NC. He is already fighting like hell in FL and VA. It seems almost pointless for him to be spending resources in NH and NV, but I am glad to see it.
Yes, this is based on polling data containing "bounce" from DNC, but also note we have not yet had full round of state polls since DNC in battleground states. The situation could be even worse that Nate shows. And Romney people have admitted to Politico a situation in OH which may be worse than the 5 point margin in PPP.
Remember, the name of the game is the electoral college.
If Romney loses NV, NH, Wi & VA the election is over unless he can find unfaithful electors.