In the years before the rise of the teachers' movement, tens of political groups were engaged in grass-roots agitation and organization throughout Mexico. Rather than composing a coherent opposition, these groups wove a tangled web of political projects that ranged from the pragmatic to the utopian. Whereas the radical opposition of earlier years had been largely confined to the Mexican Communist Party (PCM), the 1968 student movement had spawned a plethora of competing political tendencies, which included Maoists, Trotskyists, left Christians, and “Cubans” (see Introduction). Among these, just two groups were to have a decisive influence on the teachers' movement in Chiapas: the Trotskyists, who formed the hard core of the Revolutionary Workers' Party (PRT), and the Política Popular, which had rejected left-wing party politics in favor of Maoist tactics of direct mass mobilization. By the usual process of fission and fusion on the radical left, Política Popular finally appeared in Chiapas as Línea Proletaria.

Both the Trotskyists and Línea Proletaria arrived in Chiapas in 1974. The Trotskyists found their foothold in the Agricultural Technical Schools (ETAs) and played a key role in the ETAs movement of 1977 and 1978. Línea Proletaria had sent Heraclio Blanco, one of its militants from La Laguna, to “teach the teachers the theory,” as well as to begin to organize among the peasant groups that were later to form the Union of Unions, one of the most successful peasant organizations in the region (Harvey 1990a). The seeds of division were already discernible in Blanco's insistence on the differences between Línea Proletaria's position and the “extremism” of the Trotskyists.