How does a politician get more people to donate to his campaign?

Pictures of dogs, obviously.

This morning I met in Charlotte with Rally.org spokesman Nick Warhsaw, who’s in town to try to sell politicians at the Democratic National Convention on the merits of the startup’s power-of-the-masses donation software. This, remember, is the startup that raised $7.9 million purely on AngelList, chugging back its own crowdsourcing Kool Aid.

Rally is already the donations portal for a “very large percentage” of this year’s election candidates, according to Warshaw. In fact, while San Antonio Mayor Julian Castro was delivering his speech last night, visitors to his homepage were accosted with a huge “donate” button powered by Rally.

Rally, which is a bipartisan platform – Romney’s campaign is also using its tools – not only helps direct funds from small donors into the pockets of politicians, but it also seeks to understand which content helps drive donations. The technology is not yet at the level where it can understand which angle should be used in campaign photography, but it does know that when it comes to massaging constituents’ wallets, photos work better than text and long-winded email appeals.

Photos drive higher open rates, click-through rates, and conversions, Warsham says, and are much preferable to the standard letter-form appeal that candidates have been using for years. In some cases, videos also work well – but not for those verbose policy speeches. Instead, videos are best used for dramatic and emotional impact.

One day soon, Rally will have the data to be able to suggest to its clients which styles of photography – soft-focus, black and white, glamor shots – are best at eliciting donations, but for now it can call on only anecdotal evidence. And what does that tell them? Well, you’ve got to get the puppies in the picture.

Photos with animals have performed significantly better than other shots in terms of attracting donor dollars, Warsham says. And that’s why we’ve been seeing so many photos of Obama with the family dog, Bo, recently.

Naturally, that gives us a gold-plated excuse to show you this slideshow of “Obama With Dog” photos. No need to worry about that kill list – the President likes pooches! #votevotevotevotevote

This slideshow requires JavaScript.