Chile has many political parties, but Guzmán’s cleverly crafted electoral system rewards coalitions that pool their votes rather than parties that stand alone. There are two major coalitions: the center-left Concertación para la Democracia (Consensus for Democracy) and the center-right Alianza por Chile (Alliance for Chile). Even within these coalitions, there are ideological and practical tensions that obstruct their efficient collaboration.

The Concertación, which has won every presidential election since the return to democracy, consists of the centrist Democracia Cristiana (DC, Christian Democrats), the more leftist Partido Socialista (PS, Socialist Party, far less radical than in the Allende days) and Partido por la Democracia (PPD, Party for Democracy), and the Partido Radical Socialista Demócrata (PRSD, Radical Socialist Democratic Party). There is considerable ideological overlap among these parties.

The Alianza por Chile consists of the center-right Renovación Nacional (RN, National Renovation) and the ultra-right Unión Demócratica Independiente (UDI, Independent Democratic Union), but there is also ideological overlap between them. Founded by Jaime Guzmán, the more cohesive UDI has managed to make inroads into poorer neighborhoods with a populist approach, but has struggled to distance itself from its identification with the military dictatorship.

Several less-influential parties lack congressional representation: the Partido Comunista (PC, Communist Party), the Partido Humanista (Humanist Party), and the Partido Liberal (Liberal Party).