I'll let Brendan Nyhan describe his chart:
"These charts below, for instance, present the estimated probabilities of an Obama victory and current Electoral College forecasts (where available) from the political scientists Jay DeSart and Tom Holbrook, Stanford’s Simon Jackman, Emory’s Drew Linzer, Silver, Princeton’s Sam Wang, the British sports book Betfair, and the Intrade futures market (here and here).
What you're seeing is that Silver's forecast isn't an outlier. In fact, it's actually quite a bit friendlier to Romney's chances than the other models, and only a little more bullish on Obama than the betting markets.
In this way, the laughable work being done at UnskewedPolls.com is actually on the right track. If you don't like the results the models are spitting out, you need to come up with some reason that the polls those models are using have it wrong. Otherwise, any model you develop is going to show some kind of Obama victory, because right now, the polls show an Obama victory in a critical mass of swing states.
That's why there's no credible conservative alternative to Silver's model. Indeed, there's been some talk of whether there will be a conservative Nate Silver in 2016. But as Silver has said, if the data shows the Republican ticket is ahead in 2016, Nate Silver will be the conservative Nate Silver of 2016, and so will all these other forecasters who, in the final weeks of the election, mainly rely on polling data.
Related: The Nate Silver backlash.