Why auto-post when you can personally connect with friends and followers when posts are manually posted? Facebook, Twitter and Google+ - these three networking sites are your campaign's sub-identity. In real life, these websites are the public parks. People choose to go in public parks to bond with their family, friends and create more friends. During election, political candidates distribute some goodies in public parks to create buzz. The park is their ideal haven for persuasion.
Same thing with Facebook, Twitter and Google+, it's not an effective way of connecting when you're relying on auto-posting. Find time to sign-in, manually post your link and socialize with various users.