Mexico's ruling party battles leftist nemesis in key state vote

Mexico's President Enrique Pena Nieto delivers a speech during an event to recognize the contributions made by members of the Mexican foreign service, in Mexico City, Mexico, April 28, 2017. REUTERS/Edgard Garrido

ECAPTEPEC, Mexico (Reuters) - Nine decades of rule by President Enrique Pena Nieto's Institutional Revolutionary Party (PRI) in Mexico's most populous state are hanging in the balance in an election that could batter its hopes of keeping power nationally in 2018.

Polls show the National Regeneration Movement (MORENA), the new party of veteran leftist Andres Manuel Lopez Obrador, could wrest control of the state of Mexico from the PRI by winning the governorship in the June 4 state election, a result that would ramp up the momentum for his bid to succeed Pena Nieto in 2018.