For better or worse, the U.S. political season is here, but thanks to WordPress.com VIP, we now know that WordPress is the most commonly used platform for this season’s campaign sites. In a field that was previously dominated by custom-built sites, WordPress is making a strong grab for the mantle of the go-to political web platform, and between WordPress, Drupal, and Joomla, open source software is powering almost all of this season’s campaign sites. For this season alone, WordPress is powering 35% of U.S. Congressional races, 40% of U.S. Senate races, 44% of Gubernatorial races, 41% of state political parties, and both of the 2012 major political party conventions.