Explaining Michele Bachmann's Epic Collapse

I'd say two words explain Bachmann's collapse: Rick Perry.

That is, Rick Perry stole her thunder by entering the race the same weekend that Bachmann won the Ames straw poll, and Bachmann torpedoed her own campaign with her attack on Governor Perry on the Gardasil issue. I didn't really understand why she was hammering that issue at the time. It wasn't her best moment and she never recovered. Perhaps there were other campaign problems as well, organization and fundraising, and so forth. But it was Rick Perry who stopped Bachmann's momentum and her attempts to regain it by attacking Perry sunk her ever further.

The Los Angeles Times has more, "Michele Bachmann: What happened to the once-promising candidate?"