Complex sentence: Original materials for the Obama campaign used the serif Perpetua, however campaign staffers John Slabyk and Scott Thomas made the change to Gotham, and the font was used on numerous signs and posters for the campaign.
Split into simpler sentences: Original materials for the Obama campaign used the serif Perpetua. Later, however, the campaign made the change to Gotham, and the font was used on numerous signs and posters for the campaign.