Catania was the first openly gay member of the D.C. Council and one of a small number of openly gay Republican office-holders. This led to a conflict within his party when President George W. Bush spoke in favor of an amendment to the United States Constitution to ban same-sex marriage. Catania opposed the amendment and became a vocal opponent of Bush's 2004 re-election. In response, the District of Columbia Republican Committee decertified him as a delegate to the 2004 Republican National Convention. Catania announced his endorsement of the Democratic presidential candidate, John Kerry, one week prior to the convention. In September 2004, Catania left the party and became an independent, citing his displeasure with its direction on urban and social issues. He was re-elected in 2006 and 2010 as an independent.