JMHO, part of the problem is people’s perception of J.D. I can’t remember where I read this but someone opined that he reminded people of a used car salesman. When they try to think of him as their United States Senator there’s a possible built-in resistance. At least McCain seems like the senatorial model they have in their minds. I’m not sure a lot of them are idiotic enough to outright BELIEVE him on his borders pronouncements but they could have a little hope that he will listen to Sarah Palin and Tea Partiers about the border. Hope against hope, as the old saying goes...
I saw a few clips of the debate between him and McCain and that was the impression I got also. He does not have a likable personality and until he changes his persona, too may people will judge him and not his message. He comes across as a shyster.