Redstate
Posted at 2:45 pm on August 1, 2016 by Leon H. Wolf
In Presidential elections where the Republican candidate wins or comes close, you tend to see the same dynamic unfold in terms of the ideological breakdown of the electorate. The Republican wins between 80 and 85% of conservatives, the Democrat wins between 80 and 85% of liberals, and the Democrat wins moderates by some relatively small percentage. The Republican either wins or comes close based on the strength of the fact that self-identified conservatives usually outnumber self-identified liberals by around 35%-25%. This is the dynamic you saw in both 2004 and 2012, which were both very close elections.
Hidden in today's CBS's poll (not included in the crosstabs) is an indication that Trump's alienation of conservatives is the reason he is behind in this poll.
It's impossible to do with 100% accuracy without knowing the ideological breakdown of the sample, which neither CBS nor Portnoy provide (at least not that I can see, but if you assume a sample consistent with the 2004/2008/2012 electorate that is roughly 35% self-ID'ed conservatives, moving that 35% from the usual 82-15 split in favor of the R to a 64-21 split in favor of Trump equates to about a 7-8% swing in the overall electorate.
In other words, if Trump were performing as well as the average Republican candidate among conservatives, he would be winning. He's tanking (relatively speaking) among that group instead, so he is losing.
(EXCERPTED DUE TO COPYRIGHT. MORE AT LINK)
http://www.redstate.com/leon_h_wolf/2016/08/01/cbs-poll-trumps-alienation-conservatives-reason-hes-behind/
