Chris Sununu would probably cruise to reelection if he runs for a fourth two-year term as Governor of New Hampshire in 2022. If he challenges Senator Hassan, it's going to be an expensive and bloody race. If he fails to defeat her, then he probably loses the option to viably run for the presidency in 2024 or 2028.

It seems to me that Kelly Ayotte opting for a rematch against Maggie Hassan would be the lowest-risk / highest-reward scenario for Sununu, Ayotte, and New Hampshire Republicans alike.