According to Gallup's all year 2013 surveys, 9 states can right now be regarded as true toss-ups, meaning that the partisan advantage of the state's voters one way or another is less than 2.5%. In addition, 20 states + Washington D.C. lean Democratic by a margin exceeding 2.5%, while 21 states lean Republican by a margin of more than 2.5%. That gives us this map of partisan affiliation as of 2013:
True toss up: Less than 2.5% margin
30% shade: 2.5%-5% margin
40% shade: 5%-10% margin
50% shade: 10%-15% margin
60% shade: 15%-20% margin
70% shade: 20%-25% margin
80% shade: 25%-35% margin
90% shade: More than 35% margin (only Wyoming + D.C.)
So that gives us 9 absolute toss-ups and 19 if we include all states where the partisan margin is less than 5%. And in the Electoral Votes count we then get this:
Democratic states: 272 EVs (an absolute majority)
Republican states: 172 EVs
Toss-up states: 94 EVs (Ohio being the most important, followed by North Carolina, Virginia, Arizona and Wisconsin)
Nevada is the state pushing the Democrats over the victory line btw. Nevada is however 2.4% less Democratic-leaning than the Popular Vote. Pennsylvania comes second closest to determining the outcome of this hypothetical election. (Kentucky would be third, West Virginia fourth, Wisconsin fifth and Florida only sixth.)
I guess people will be surprised to see Arizona as a true toss-up, while Colorado and New Hampshire lean (slightly) Republican.
Personally I think Florida has one of the most interesting partisan divides right now. According to Gallup's numbers, Florida already leans Democratic by a margin of 4.6%, which is considerably higher than a number of states including:
-1.6% more Democratic-leaning than Pennsylvania
-1.9% more D-leaning than Nevada
-3.6% more D than Wisconsin
-4.2% more D than Ohio
-5.2% more D than North Carolina
-5.2% more D than Arizona
-5.6% more D than Virginia (!)
-6.7% more D than Iowa (!)
-7.5% more D than Georgia
-8.4% more D than Colorado (!) [mirroring many of the 2016 polls so far]
-8.5% more D than Texas
-8.6% more D than New Hampshire (!)
If Gallup is right and their 2013 numbers remain stable for 3 more years, the 25 most important battleground states come 2016 might in fact be these (and in this order of importance):
1. Nevada - the tipping point state (yet 2.4% more Republican than P.V.)
2. Pennsylvania - D +0.3% relative to Nevada
3. Kentucky - R +1.2% relative to Nevada
4. West Virginia - R +1.4% relative to Nevada
5. Wisconsin - R +1.7% relative to Nevada
6. Florida - D +1.9% relative to Nevada
7. Minnesota - D +2.9% relative to Nevada
8. North Carolina - R +3.3% relative to Nevada
8. Arizona - R +3.3% relative to Nevada
10. Maine - D +3.4% relative to Nevada
11. Virginia - R +3.7% relative to Nevada
12. Oregon - D +3.9% relative to Nevada
13. Washington - D +4.6% relative to Nevada
14. Louisiana - R +4.7% relative to Nevada
15. Iowa - R +4.8% relative to Nevada
16. Georgia - R +5.6% relative to Nevada
17. Missouri - R +5.8% relative to Nevada
18. Arkansas - R +6.4% relative to Nevada
19. Colorado - R +6.5% relative to Nevada
20. Texas - R + 6.6% relative to Nevada
21. Michigan - D +6.7% relative to Nevada
22. New Hampshire - R +6.7% relative to Nevada
23. Indiana - R +7% relative to Nevada
24. New Mexico - D +8.5% relative to Nevada
25. Mississippi - R +9.1% relative to Nevada
Notice how Kentucky is shaping up to be much more important than New Mexico.
