Think about all the glurgey emails you get about puppies and kittens and God. I think people send these of their own accord. Which leads me to believe these are probably made up by "civilian" supporters of the candidates, then grow legs according to merit.
I'm not sure whether I would consider the above political though. It's the sort of photo that would be given a caption on one of our comedy news shows. To me it's not about immigration or aren't-black-people-funny and more about someone getting "famous" and suddenly being deluged with poor relations. It would work as well if it was a photo of white people squeezing into a phone box - John McCain's relatives suddenly eager to come over for tea. Okay not that funny, but I'm not the one sending it round the internet