My hunch was that the Ayotte trial balloon was a Judd Gregg orchestration, since he's really the only prominent big name Republican in-state who can basically ignore Sununu Senior's plans for his son.
This news (h/t Pindell) confirms my suspicion that there is a skirmish going on in the state elephants between Sununu and others over control of the senate nominee:
He indicated that if his son decides to run - a decision the father expects within a week or so - Ayotte will step aside.
"I think, if my son runs, there will not be a primary," he said.
Pater Sununu previously indicated there wouldn't be a decision until the fall. Now they're scared that the Ayotte train is leaving the station.