Updated

President Enrique Pena Nieto has signed Mexico's most sweeping education reform in seven decades, a change widely expected to weaken the country's powerful teacher's union.

Pena Nieto signed the reform Monday after it was approved by Mexico's congress and the majority of state legislatures. The legislation creates a system of uniform standards for teacher hiring and promotion, in place of a system that critics said placed excessive power in the hands of the union, even allowing teachers' positions to be sold and inherited.

The reform also will allow the first census of schools, teachers and students. Until now, there has been no official count of the Mexican education system.

The reform was a plank of a pact signed between Pena Nieto's Institutional Revolutionary Party and the two main opposition parties.