Bachmann is so very very out there that if she won the nomination it would be tantamount to giving the election away. And there's a good chance there might be another SC opening after 2012. You never know. So I think to the extent that they exist the Republican powers that be will ensure that Bachmann does not win.

"When the snows fall and the white winds blow, the lone wolf dies but the pack survives."
Winter is Coming

Now this is the Law of the Jungle—as old and as true as the sky; And the wolf that shall keep it may prosper, but the wolf that shall break it must die.
As the creeper that girdles the tree-trunk, the Law runneth forward and back; For the strength of the Pack is the Wolf, and the strength of the Wolf is the Pack.