Original: In 1934, the Communists changed their line, and the four left-wing parties came together in the Popular Front, which won the 1936 elections and brought Blum to power as France's first SFIO Prime Minister.
Simplified: In 1934, the Communists changed their line, and the three parties came together in the Popular Front, which won the 1936 elections and brought Blum to power as France's first Socialist Prime Minister.