I dont think race has a damn thing to do about it.
He is continually making gaffes, hasn't policed things like titty bar trips with GOP money, embarassed the party by spending a ton of $ to move the convention from Wash DC to Hawaii....
And above all, in a time when he should be earning RECORD amounts of cash to defeat the dems in the fall, he ain't earning.
He's a terrible leader, and the GOP needs someone strong, someone known, and someone shrewd and respected, to take the job. IMAGINE the $ that would come rolling in tomorrow if you had a guy like Jeb Bush come in, fire a few people, and take a public stance that every cent you send the GOP will be used wisely.