Build a Strong Base

• If you win over a partisan, he is a guaranteed vote. Further, you can point to your partisans as living examples of your beliefs. Nobody can say you don't stand for something when your partisans are so passionate about the ideals you espouse. If many of your partisans are affiliated with another cause, it makes it easier to court organizations concerned with that cause; for example, if many of your partisans are in unions, it may be a good idea to court endorsements from union officials.
  
  

Campaigning

• Partisans are advantageous for what they do for you themselves: They make donations, plant lawn signs, buy bumper stickers, attend rallies, write blog posts and otherwise spread the word about you, not only to their friends and families, but to anyone who comes in contact with them. As such, they provide invaluable funds, energy and free publicity to your campaign. Part of the success of the Obama campaign in 2008 was its effective mobilization of such grassroots support.
  
  

Extremism

• A major disadvantage of winning partisans is the risk of association with extremism. If partisans go to your rallies and shout vicious insults about your opponent or if they fake being attacked by a supporter of the opposition, that reflects poorly on you. While individual actions are a problem, more serious damage can occur when your partisans are tied to controversial organizations, such as the controversy surrounding Obama's affiliation with the community action organization, Acorn.
  
  

Alienating Voters

• In America, partisan politics has a reputation for being small-minded and more concerned with shouting than listening. If you are viewed as too partisan, it will alienate independents and moderates, invaluable for winning elections. Partisans can keep you on your game -- if you renege on a campaign promise or go against your principles, they will let you know about it and may support an opposing candidate in the future. According to a Salon.com article, partisans on both sides of the Israeli-Palestinian conflict felt that Obama betrayed them and would not vote for him again in 2012.