I think his campaign says that Abraham was never hired to be an acting campaign manager - but merely a representative to DC or something like that. However, Thompson does seem to have a pattern of hiring staff that lean strongly to the moderate wing of the Republican party. This really does surprise me if he truly is the Conservative Stalwart we claims to be.
It's word play.
"Mr. Thompsons new communications director, Linda Rozett, said that former Energy Secretary Spencer Abraham, a Republican who is also a former senator from Michigan, had joined Mr. Thompson in a major role that would be considered campaign manager if the staff was using the terminology of a presidential campaign. (But they are not.)"