According to ChicagoBusiness.com:
Sender LLC is a Chicago brand consultancy and design studio whose clients include Crain’s. “We were looking at the “o” of his name and had the idea of a rising sun and a new day,” Mr. Sender said. “The sun rising over the horizon evoked a new sense of hope.”
ChicagoBusiness ArticleIn addition, it should be noted that the stripes also suggest the plains, the breadbasket of America. If you bother to go online and do your research you will find that some graphic designers are hailing it as one of the best campaign logos EVER. In fact, 2 republican candidates have used it as the basis for their logos. As someone who has studied branding and graphic design, I agree, it's brilliant.