Mexico passed sweeping education reforms in February which were meant to take power from teachers' unions and give it back to the government.
The move was aimed at improving the country's abysmal schools, and make their students more competitive in an expanding economy.
Although states are now voting to ratify the reform, dissident teachers' groups in the southwestern state of Guerrero are protesting against it ever being enacted
On Thursday, thousands of masked staff walked during a blazingly hot day in the streets of Chilpancingo, capital of impoverished Guerrero, to show their opposition to President Enrique Pe?a Nieto's education reforms. They are mainly opposed to evaluations that the reforms would set in place.
Proceso Gonzalez teaches high school biology in the mountains of Guerrero. The small village where he works is seven to 10 hours away from Chilpancingo, depending on whether it rains and the condition of the dirt roads.
Gonzalez says his students are so poor they sometimes don't eat. Gonzalez feels it would be unfair for him to be evaluated based on their performance.
"My students sometimes only eat two small tacos a day. It's not fair to compare them to students in Monterrey," he says, referring to one of Mexico's richest cities.
Situations such as this, in the teachers’ view, underscore their dilemma.
The teachers are facing nearly unanimous support of the reforms from Mexico's political class. Pe?a Nieto pushed through the education reforms in February to wide acclaim.
Across Mexico, teachers are often stereotyped as uneducated, unprepared and blind followers of their often-corrupt unions. They're also sometimes seen as violent.
On Wednesday, some of the teachers and their supporters sacked the offices of the three main political parties' offices in Chilpancingo.
Despite all that, the teachers are proving to be a thorn in the side for Pe?a Nieto.
Abroad, the 46-year-old president is still riding a wave of popularity five months after taking office. He made TIME's 100 most-influential list, and was compared to US presidents Ronald Reagan and Barack Obama in the magazine's write up.
In Mexico, he's had a rough week, however, in large part because of the rabble-rousing teachers.
Pe?a Nieto's Pact For Mexico, an alliance with opposition parties, has also been put at risk after audio recordings emerged that allegedly showed members of his Institutional Revolutionary Party discussing how to use government resources to mobilise voters in state elections.
While the education reforms look likely be ratified by the states, the battle will be tougher than Pe?a Nieto thought, taking its toll on him and his government.