McCain's fervent support of the troop increase will only hurt him unless something drastic changes.
I'm not convinced that it's hurting him much in the GOP primary race. The general election is a different story. Yes, his support in this particular poll is low, but I think it's an outlier. We haven't seen such low support for McCain in other polls.
This graph:
http://www.pollster.com/1TopRepslarge1.phpactually shows that, at least as of polls taken a week ago, McCain's GOP support was as strong as ever. Other than this one poll by Rasmussen, have we seen McCain's GOP support trailing off at all since then?