Mexicans voted for a new president Sunday after a campaign dominated by calls for economic growth and debate about how to proceed with a bloody war on drug cartels that has killed nearly 50,000 people since 2006.
Enrique Pena Nieto, a 45-year-old with boyish good looks from the centrist Institutional Revolutionary Party (PRI), held a significant lead as lines formed outside voting stations in Mexico’s 31 states.
His victory would mark the return to power of a party whose system of top-down politics and patronage controlled the Mexican presidency through much of the 20th century.
But a smooth victory was far from assured.
Attention has increased in recent weeks for leftist candidate Andres Manuel Lopez Obrador, a former Mexico City mayor whose supporters nearly brought the nation to its knees with protests after he lost the 2006 presidential election by less than a single percentage point.
The question on many minds was whether a similar standoff could unfold if the final tally is close.
The most recent pre-election polls showed Mr. Pena Nieto with 45 percent support and Mr. Lopez Obrador, 58, of the Party of Democratic Revolution (PRD), with about 29 percent.
Josefina Vazquez Mota, 51, of the conservative National Action Party (PAN) and the first woman to run for president on a major-party ticket in Mexico, had 24 percent support.
A fourth candidate, Gabriel Quadri de la Torre, 57, is the candidate of the New Alliance Party, which has links to the powerful teachers union. His poll support remains in the low single digits.
Mexican voters also were electing 500 members of the lower house of Congress and 128 senators.
They also selected Mexico City’s mayor and governors in the states of Chiapas, Guanajuato, Jalisco, Morelos, Tabasco and Yucatan.
Christopher Sabatini, who directs policy at the Americas Society and Council of the Americas in New York, said it is unlikely that Mr. Lopez Obrador’s supporters would be able to galvanize an election challenge as effectively as they did six years ago.
“We’re talking about a margin of difference that’s probably going to be a lot larger this time around,” said Mr. Sabatini, adding that Mr. Lopez Obrador’s supporters may stage demonstrations challenging the legitimacy of Mexico’s overall political system, but they likely will struggle to claim the race was stolen in a close vote.
“I don’t think he’ll directly contest the elections,” Mr. Sabatini said. “I think what they’re going to contest is the corruption of the system generally, a system under which the old PRI machinery has now roared back to life in the wake of the PAN’s failure of the last 12 years.”
A victory by Mr. Pena Nieto will signal defeat for PAN, which has held power since 2000, first under President Vicente Fox and then for the past six years under President Felipe Calderon.