Michelle is playing the role of what they call in bike racing “The Lead Rider” who sacrifices themselves by jumping out early and drawing their teammate’s competitors. This clears the way for their designated teammate to win the race. This idea was expressed by Freeper dfwgator and I think it makes a good point.
I think Palin is waiting to see if Bachmann runs. If she does, Sarah may not run, but support her flank, then take a cabinet post. Just a theory.