In the 2001 congressional elections, the conservative Independent Democratic Union (UDI) surpassed the Christian Democrats for the first time to become the largest party in the lower house. In the 2005 parliamentary election, both leading parties, the Christian Democrats and the UDI lost representation in favor of their respective allies Socialist Party (which became the biggest party in the Concertación block) and National Renewal in the right-wing alliance. In the 2009 legislative elections in Chile, the Communist Party won 3 out of 120 seats in the Chamber of Deputies for the first time in 30 years (the Communist Party was not allowed to exist as such during the dictatorship).