I don't think the left really minds if Perry is the Republican nominee. By some polling, the majority of Americans still blame Bush for the economy (If you say, "I inherited it" enough times people will start to believe you. So the electorate may not be in the mood for another plain-spoken Texas governor, especially after the media makes the cowboy label stick.
Being painted as Bush 2.0 could be Perry's downfall.
That is my biggest concern. I will keep my eye on the general election matchups and see how Perry polls among independents and moderates. If he polls well there, then I think he can win. Really though, I think this election will be all about the economy. Whoever has a good track record on that issue stands a good chance against Obama.