Frossard resigned and left the PCF in 1923 to found a dissident United Communist Party which later became the Communist Socialist Party (but Frossard himself rejoined the SFIO). The general secretariat of the Party was shared by Louis Sellier (center faction) and Albert Treint (left-wing faction). At the same time, Boris Souvarine was expelled from the Communist International and the PCF due to his sympathy for Leon Trotsky. In the 1924 legislative election, the PCF won 9.8% of the vote and 26 seats, considerably weaker than the SFIO. But under the leadership of the left-wing faction, priority was given to general strikes and revolutionary actions rather than elections. In the French Parliament, the PCF's first elected deputies were opposed to the "Cartel des Gauches" coalition formed by the SFIO and the Radical Party, which governed between 1924 and 1926. In order to reconcile the various factions of the party, Pierre Sémard, railroad worker and union activist, was chosen as the new secretary-general. He wanted to put an end to sectarianism, which was criticized by communist officeholders and leaders of the CGTU. Most notably, he proposed alliances with other left-wing parties (including the SFIO) in order to combat fascism. This strategy was criticized by the board of the Communist International as "parliamentarist". At the same time, the party campaigned against French colonialism in Morocco (the Rif War), leading to the detention of some PCF members, including Sémard. On his release from prison, he became more and more controversial. Only 11 PCF candidates were elected in the Chamber of Deputies in the 1928 election, although the PCF increased its support to 11%. In 1927, in the Soviet Union, Josef Stalin sidelined his opponents (Zinoviev, Kamenev and Leon Trotsky) and imposed a strict "class against class" line on the Communist International. In France, a Stalinist committee took control of the PCF . Its most influential figures came from the Communist Youth, notably Henri Barbé and Pierre Célor. They applied the "class against class" political line of the Communist International, denouncing social democracy and the SFIO as akin to bourgeois parties. Simultaneously, the new leadership purged dissidents, like Louis Sellier, former secretary-general, who created the Worker and Peasant Party, which merged with the Communist Socialist Party to form the Party of Proletarian Unity (PUP).