Head of Mexico's ruling PRI steps down after electoral drubbing

Mexico's president-elect Enrique Pena Nieto (L) and congressman Manlio Fabio Beltrones attend a meeting with newly elected senators and lawmakers of the Institutional Revoluntionary Party (PRI) in Mexico City August 9, 2012. REUTERS/Tomas Bravo

MEXICO CITY (Reuters) - The president of Mexico's ruling Institutional Revolutionary Party, or PRI, announced his resignation on Monday, two weeks after the party of President Enrique Pena Nieto suffered a humiliating defeat in regional elections.

Manlio Fabio Beltrones, a former governor and veteran federal lawmaker, announced his decision to step down after the PRI won only five of the dozen governors races up for grabs in the June 5 vote. It previously held nine of them.