This is a huge point, none of the others (except Newt) have been vetted AT ALL. Bachman used to send people who couldn't pay their taxes to jail when she worked for the IRS. It was her job, but man will she get beat over the head for that!! All these guys, many most likely not anywhere near the morality level of Sarah (FReepers, please don't show your stupidity arguing this, you KNOW it's true), definately have had a clear path so far.
If Sarah announces she is not running, just watch the press attack them all like deamons released from the gates of hell!!!
Then, she can hold off on deciding to take the heat off the other candidates.