The CNTE, which broke off from the SNTE in 1979 because of a lack of representation from the southwestern states in the union leadership, has moved to fill the void by staging its own protests.
To express its discontent with the education reform, the CNTE twice blocked the road leading to the Mexico City International Airport, once in mid-August and again in early September.
While SNTE members in Oaxaca were already supporting the CNTE, there has been little support from members of the larger union in other parts of the country.
While the CNTE demonstrations have been loud and noisy, leaders have said they do not object in principle to the concept of teacher evaluations, only to what the union considers a "punitive" scheme devised by the government to weed out many teachers.
Some analysts say the complaint is legitimate, and teachers from both from the SNTE and the CNTE have reason for concern.
The attention to the direct impact of education reform on teachers has overshadowed another CNTE complaint, which is that the new requirements could threaten the right of all Mexicans to receive a free public education.