PRI leader Pena Nieto is apparent winner of Mexican presidential election

In a turning point for Mexico, the once-dominant Institutional Revolutionary Party prepared Sunday night to celebrate what a spokesman called the resounding triumph of its presidential candidate, Enrique Pena Nieto.

Throngs of supporters flocked to the headquarters of the PRI, as the party is known for its Spanish acronym, to celebrate the anticipated return to power of a party that kept a monopolistic grip on Mexico for an uninterrupted seven decades.