I submit that the two are not mutually exclusive and that he can be both.
At the risk of hewing to Godwin’s Law, Hitler was an ideologue too but obviously waged an effective campaign (many of them, in fact) to put his agenda in place.
Obama is no doubt an ideologue but he is, as usual, attempting to modify a pocket watch with a pipe wrench and frustrated by the results.
The USA is not a one-party state and there is significant opposition among the populace; Nazi Germany was (never mind abandoning “democracy”) and also had a significant number of its population on board. Apples and oranges comparison.