yeah, it's not that. She barely eked by her opponent in the last election, and knows with the scandals piling up, she'd be toast in 2014.
The real question is why the scandals even became scandals. Sounds like a disgruntled former staffer ratted her out, and either left politics or went to work for someone else.
I'm guessing if she was still electable the GOP would've worked with the Democrats to bury the issue, but her more "exceptional" political positions have attracted too much controversy, and served as a fundraising boon for her opponents. This made it easy for the Minnesota GOP to find a more palatable candidate to replace her.
basically... her extremism upset the delicate jerrymandered balance in national politics: she was in a safe GOP district (as most of the country is), but her idiotic positions actually made it possible for democracy to happen and a challenger to win.
I think
THIS shows how things really work. He knows he has no shot at beating a palatable GOP-insider in a GOP district.