I don't know for sure whether it was intentional, but Romney appeared on stage in front of this official campaign banner:
See, there's a very racist stereotype about black people being "lazy and shiftless," and another one that has to do with "welfare queens" who don't want to work. So when you create a disgusting slogan like this one, it serves as a dog-whistle, stoking white racist anger while also offending every black person in the country.
Yeah, it was probably intentional. The Republican Party's use of the Southern Strategy is well-documented and verified by actual Republican leaders.