Romney is afraid of Newt. He [and his PAC] put out ads that lie or twist the truth ($2million/day of ads in FL for 10 days leading up to the vote].
Newt said he was blind-sided by Mitt’s flat out lies during the FL debate but will be prepared to deal with him doing that in the coming debates. So Mitt pulls out of the GA debate (Newt’s turf), packs the AZ debate with his people (like FL); the Reagan Library debate is pulled.
I expect Newt will be ignored for much of the AZ debate and if he zings Mitt, his supporter packed auditorium will boo. And when grinning, stuttering Mitt makes a funny, they will all laugh and cheer.