Popular front

The Comintern's Popular Front policy 1934–1939
In response to the growing threat of fascism in the 1930s, Communist parties that were members of the Comintern (then largely under the control of Joseph Stalin) adopted a policy of forming broad alliances with almost any political party willing to oppose the fascists. These were called "popular fronts". Some popular fronts won elections and formed governments, as in France (Front Populaire), the Second Spanish Republic, and Chile. Others never quite got off the ground. There were attempts in the United Kingdom to found a Popular Front against the 's appeasement of Nazi Germany, between the Labour Party, the, the Independent Labour Party, the Communist Party, and even rebellious elements of the under Winston Churchill, but they failed mainly due to opposition from within the Labour Party but incompatibility of Liberal and socialist approaches also caused many Liberals to be hostile.

The Popular Front policy of the Comintern was introduced in 1934, succeeding its ultra-left "Third Period" during which it condemned non-Communist socialist parties as "social fascist". The new policy was signalled in a Pravda article of May 1934, which commented favourably on socialist-Communist collaboration. In June 1934, Léon Blum's Socialist Party signed a pact of united action with the French Communist Party, extended to the Radical Party in October. In May 1935, France and Russia signed a defensive alliance and in August 1935, the Comintern's Seventh Congress officially endorsed the Popular Front strategy. In the elections of May 1936, the Popular Front won a majority of parliamentary seats (378 deputies against 220), and Léon Blum formed a government.

In Italy, the Comintern advised an alliance between the Italian Communist Party and the Italian Socialist Party, but this was rejected by the Socialists. Similarly, in the United States, the CPUSA sought a joint Socialist-Communist ticket with Norman Thomas's Socialist Party of America in the 1936 presidential election but the Socialists rejected this overture. The CPUSA also offered critical support to Franklin Roosevelt's New Deal in this period. The Popular Front period in the USA saw the CP taking a very patriotic and populist line, later called Browderism.

The Popular Front period came to an end with the Molotov-Ribbentrop pact between Nazi Germany and Russia, at which point Comintern parties turned from a policy of anti-fascism to one of advocating peace.

Critics and defenders of the Popular Front policy
Leon Trotsky and his supporters roundly criticised the Popular Front strategy. In the first place, Stalin had used the Popular Front as a tool to oppose Trotsky and other dissidents outside Stalin's immediate control. Additionally, Trotsky believed that only united fronts could ultimately be progressive, and that popular fronts were useless because they included non-working class bourgeois forces such as liberals. Trotsky also argued that in popular fronts, working class demands are reduced to their bare minimum, and the ability of the working class to put forward its own independent set of politics is compromised. This view is now common to most Trotskyist groups. Left communist groups also oppose popular fronts, but they came to oppose united fronts as well.

In a book written in 1977, the Eurocommunist leader Santiago Carrillo offered a positive assessment of the Popular Front. He argued that in Spain, despite excesses attributable to the passions of civil war, the period of coalition government in Republican areas 'contained in embryo the conception of an advance to socialism with democracy, with a multi-party system, parliament, and liberty for the opposition'. Carrillo, however, criticised the Communist International for not taking the Popular Front strategy far enough — specifically for the fact that the French Communists were restricted to supporting Leon Blum's government from without, rather than becoming full coalition partners.