The Tumblr wasn’t so much a mechanism of persuasion as it was a brand ambassador — the brand, in this case, being a president. The real power of social, Olin points out, isn’t just sharing; it’s getting people to ask their friends to do things — “because that’s so much more powerful than for us to ask less engaged people to do it.” That kind of action-by-proxy means something slightly different on Tumblr than it does on Twitter and, particularly, on Facebook, where users are more used (and more numbed?) to traditional brand messaging. The sincerity of the platform encourages a special kind of engagement. If Facebook and Twitter — not to mention TV and radio — represented something more like the Big Tent approach to campaign communications, the one-size-fits-most strategy of politicking, Tumblr offered an inverse proposition: the niche, networked.