I wonder if it even registers that he is barely acceptable exactly because of his wretched record on immigration.
This should be easy to prove. Find me a candidate who won with anti-illegal rhetoric? Surely neither Tancredo or Romney. Surely not that US Representative from Arizona who lost in 2006.
At best, this issue may be enough to defeat a candidate in a primary but not enough to win in a general election. The problem is those with a degree or training more than college are inclined to be statistically more prone to support tolerance on this and other issues.
Whether they are right or wrong in this view makes little difference. The bottom line is it does make a difference in voter preference. Not the only issue, but a key issue determining a general approach to governance.