This type of advertising is called Testimonial and it's using the technique known as Celebrity Endorsement. In testimonial advertising the message is saying "this person says this product/politician is good", and the celebrity endorsement refers to the link between the product and the famous person. This technique is mainly used in sports, when famous athletes only wear one type of brand, they are telling you "this product is good because this famous person always uses it".
I would say bandwagon. The statement can be pretty much be translated as "All your idols are voting the governor, you should too." Appealing the reader to vote the governor base on the actions of their idols and not by the facts or the belief of the reader.
