Chile is one of the few Latin American nations in which Marxist parties exist that can claim a mass following. Both the Socialist and Communist parties are directed by persons who have adapted to legislative roles within the constitutional "rules of the game". Joined together since 1956 in a Popular Action Front (FRAP) electoral coalition, the SP and CP have over the years managed to forge a stable and expanding constituency among lower class voters. Benefiting from popular disillusionment with the failure of the Frei (Christian Democratic) Government to implement a rapid "anti-oligarchic" transformation of socio-economic structures (the so-called "Revolution in Liberty"), these two parties increased their popular support from less than 22 per cent in 1965 to almost 30 per cent in the 1967 municipal elections