If it helps, http://marginoferror.org/2012/11/08/aggregating-the-aggregat... reports a RMSE for just his state-level margin of victory.

But as part of a project I was aggregating predictions as well, and for his state wins I got 0.02833, for his Senate-level predictions I got a Brier of 0.04484545, and for his Presidency win & Senate wins & state wins, I got a Brier of 0.03710118.

Hope this helps!