American Bridge 21st Century

American Bridge 21st Century or AB PAC is a liberal American Super PAC and opposition research group that supports Democratic candidates and opposes Republican candidates. Founded by David Brock in 2010 and associated with Media Matters for America, the organization is one of the largest networks of liberal donors in the U.S.

American Bridge 21st Century is an opposition research hub for the Democratic Party. The group employs trackers to physically monitor and surveil Republican candidates and officials and uses social media to deploy its findings.

According to Politico, American Bridge 21st Century is "one of the largest and most public facing organizations affiliated with the Democratic Party." In 2020, the group spent $73 million, "making it one of the most prolific outside spenders on either side of the aisle." In 2024, the group expanded to target U.S. House candidates for the first time; it had previously focused only on presidential races, the U.S. Senate, and state races like governorships. American Bridge 21st Century spent $140 million on ads attacking Donald Trump in the 2024 election.