Most partisans support the party to which they are affiliated; that has been true for a long time. I was taking issue with IceSpear's guess that 92% of Republicans will support Stewart. The point you make about there being a higher rate of defections actually applies well here. It's possible that Kaine may get as many as 10-15% of Republicans, especially if he is winning by twenty percentage points.
Usually, but some elections can produce ticket splitting that doesn't extend beyond that race
(or certain kinds of races). The entire South's political history from the 60s to 2010 is proof of that, but for Virginia, the Senate election in
1988 and
2008 produced results that aren't possible without a sizable number of votes from otherwise reliable Republican voters.
