[3] As leader of that teachers' union, Lombardo Toledano entered the Confederación Regional Obrera Mexicana (CROM), the largest and most powerful union confederation of the day and a key supporter of the regimes of Presidents Plutarco Elías Calles and Álvaro Obregón.

Lombardo Toledano served as the house intellectual for CROM, not benefiting directly from its corruption but acquiring access to power instead.

Lombardo Toledano then served as interim Governor of Puebla in 1923, was a councilman in the Federal District in 1924 to 1925, and was a congressional deputy from 1926 to 1928.

[3] In 1925, during his tenure as a councilman, he met with the colleague Juan Rico and chose the day March 13th to celebrate the 600th anniversary of the founding of Tenochtitlan.

[4] CROM lost most of its influence in 1928 after a right-wing Roman Catholic associated with the Cristero movement assassinated Obregón.

Cárdenas led a demonstration in Monterrey in which he called for unification of the various labor organizations into one national body associated with the PRI, then named the Partido Revolucionario Mexicano.

In both cases, however, the unions returned under orders to accept unity at any cost as part of the party's Popular Front policy.

However, he had even stronger support from the Soviet Union during the Popular Front era than the nominal leaders of the PCM.

He referred to himself in the first person ("yo") sixty-four times in that speech — a fact noted by some newspapers, who proceeded to nickname him the "Yo-yo Champion".

Lombardo Toledano launched two publications (a magazine called América Latina and a daily named El Popular) while continuing to publish books, pamphlets, and newspaper articles.