Here are videos from the Satva Design Studio about the creation of the red and blue Obama "O" logo for the 2008 campaign, retooled for Organizing for America and a key element in the Obama 2012 logo. In 2008, the "O" with the stripes was used to spell Obama. In 2012, that same versatile logo is now the zero in 2012; in other applications the logo still represents Obama.
Below, from the intro to the video:
"Creative director Sol Sender tells the story of conception and birth of the Obama 08 logo, including the strategy behind it, developmental concepts and finalist designs for the identity not chosen by the campaign. Sender, now a strategist with design agency VSA Partners (www.vsapartners.com) in Chicago, was creative director and principal of his own design firm, Sender LLC, when he was hired to create the campaign logo. In the fall of 2006, Sender and his team were engaged to do the work by MODE, a Chicago-based motion design studio with an existing relationship with David Axelrod, the Obama campaigns chief strategist. Obama 08 campaign took on design responsibility for the logo in mid-2007, and extended the identity across multiple applications."