MEXICO CITY – The arrest of Mexico's most powerful union leader echoes the hardball tactics of Mexico's once-imperial presidency while pushing forward an education reform that Enrique Pena Nieto has made a centerpiece of his new administration.

Elba Esther Gordillo, known for flashing her Hermes handbags and heels, stood behind bars Wednesday in a grim prison in eastern Mexico City as a judge read off charges of embezzlement and organized crime. The arrest sidelined a woman who had tried to mobilize teachers to block a schools shake-up designed to end her control over hiring and firing of teachers across the country.

It also sent a message to other union bosses and business magnates: Don't get in the way of Pena Nieto, whose Institutional Revolutionary Party has newly returned to the power it held for seven straight decades, when incoming presidents often crushed those who challenged them.