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A fresh face for the old guard: Enrique Pena Nieto claims Mexico election win

Alexandre Meneghini / AP

Enrique Pena Nieto, presidential candidate for the Revolutionary Institutional Party (PRI), greets supporters at his party's headquarters in Mexico City as exit poll results begin to come in for general elections in Mexico early Monday, July 2, 2012.

Alexandre Meneghini / AP

Supporters of Enrique Pena Nieto gather at PRI headquarters in Mexico City as exit poll results begin to come in on July 1, 2012.

Reuters reports from MEXICO CITY — The party that ruled Mexico for most of the 20th century claimed victory in a presidential election on Sunday as a senior election official said the party's candidate, Enrique Pena Nieto, held an irreversible lead over his rivals. President Felipe Calderon congratulated him on his win.

NBC Latino: Meet Mexico's new president

Pena Nieto, on track to return his once long-dominant opposition Institutional Revolutionary Party (PRI) to power, had between 37.9 and 38.55 percent of the vote, ahead of second-placed leftist challenger Andres Manuel Lopez Obrador, who had between 30.9 and 31.86 percent of the vote. Read the full story.

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Alexandre Meneghini / AP

Supporters of Enrique Pena Nieto hold newspapers with his picture on the front page, at the party's headquarters in Mexico City on July 1, 2012.

Henry Romero / Reuters

Supporters of Andres Manuel Lopez Obrador, presidential candidate for the Party of the Democratic Revolution (PRD) react after exit polls showed him to be in second place, in Mexico City on July 1, 2012.

Enrique Peña Nieto of the Institutional Revolutionary Party is leading in the polls for president in Mexico. NBC's Mark Potter reports.