I understand your concern but it is way too late and Republicans won't pull the same bull**** the Democratic Party leadership did to presumably install Harris(re: hasn't been finalized yet).
I would also dispute your contention that Sununu has a better chance than President Trump. A large percentage of the middle/working class is a President Trump stronghold that Sununu probably would not capture.
You are correct that this maybe the just chance to maintain sanity in the USA and keep our country as a Constitutional Republic based on the rule of law.
Among the latter, under pretence of governing they have divided their nations into two classes, wolves and sheep.”
Thomas Jefferson, Letter to Edward Carrington, January 16, 1787