As far as I can tell, the Obama campaign was the first ever to sell t-shirts with the candidate's portrait on it. And there were a lot of different designs that featured his image, often sold independently.

Presidential campaign t-shirts have been around since 1960, when John F. Kennedy's image as a war hero was promoted by a t-shirt design with a PT-boat on it to celebrate the Democratic candidate's valor during World War II, when a Japanese destroyer sank his vessel. But Kennedy's portrait was not displayed.