Addressing his Cabinet and hundreds of dignitaries at a celebration of his first 100 days, Pena Nieto jubilantly pledged to maintain the breakneck tempo.
"The intensity won't be passing. The pace of work will keep up. We didn't come just to govern, but to transform," he declared.
The new president pushed through the most sweeping education overhaul in seven decades, a potentially far-reaching reengineering of Mexico's deeply dysfunctional education system that calls for merit-based teacher hiring and promotion to replace a system in which union domination meant jobs were inherited and sold.
Teachers' union head Elba Esther Gordillo, one of the most powerful-yet-reviled people in Mexico, had pledged to fight the plan that passed Feb. 25, but then was arrested the next day on charges that she embezzled $160 million.
Gordillo rose to her influential position thanks to earlier PRI leaders, although she had strained those ties by supporting other parties in recent years.
Last week, Pena Nieto put forward a set of constitutional and legal changes that he pledged will drive down some of the world's highest cellphone prices and bring programming choice to a country almost entirely dominated by two television magnates.
The largest broadcaster, Televisa, long has been seen as a staunch ally of the PRI. Slim helped build his fortune when he bought Mexico's failing national telephone company at a bargain-basement price from a PRI government. Slim's Telmex controls 80 percent of Mexican landlines and 70 percent of the mobile-phone market. Emilio Azcarraga's Televisa has 70 percent of the broadcast TV market and more than 45 percent of cable television.
Pena Nieto has shown "that yes, he has the capacity to take decisions like arresting Elba Esther Gordillo, difficult decisions that require strength," said Jose Antonio Crespo, a historian and researcher at the Center for Economic Research and Teaching in Mexico City. "These are good signs that's he's willing to get into serious reforms, along with the opposition."