I don't see why Hassan would jump in. She's in a better position to run for Governor, and being Governor is more powerful than being a Senator. That of course means Ayotte might slide to a re-election.
In terms of general influence and power, being a Senator is generally considered more influential than the governor of a small state (how many people talk about Jack Dalrymple?) but less than governor of a large state (the job of Governor of Texas is relatively toothless, yet Perry and Bush still used it as a springboard higher).
