MEXICO CITY -- Mexico's old guard prepared to sail back into power after 12 years Sunday as the leader of the party said all exit polls "irreversibly" favored its presidential candidate, Enrique Pena Nieto.
Three major exit polls showed Mr. Pena Nieto of the Institutional Revolutionary Party, or PRI, with about 40 percent of the vote in the presidential election, nearly 10 points ahead of his nearest challenger. Two were exit polls and the third a "quick count" based on the actual vote.
The Federal Elections Institute said that with 5 percent of the vote counted, Mr. Pena Nieto had 36 percent, Andres Manuel Lopez Obrador of the leftist Democratic Revolution Party 31 percent, and Josefina Vazquez Mota of the ruling National Action Party just under 28 percent.
Ms. Vazquez Mota conceded, as did New Alliance candidate Gabriel Quadri, who had single-digit support. That left Mr. Lopez Obrador as the only holdout.
PRI President Joaquin Coldwell said PRI would await the official count before declaring victory.
PRI appeared likely to retake at least a plurality in the two houses of congress and some governorships.
Critics say PRI's 71-year rule was characterized by authoritarian and corrupt practices. But it has sought to portray itself as a group that has been modernized and does not seek to return to the old ways. It held a strong lead throughout the campaign.
"Enrique Pena Nieto appears to be accomplishing what many thought would never happen again: the return of a strong and dynamic PRI," said Eric Olson of the Washington-based Mexico Institute. "The question: How will they govern?"
Mr. Lopez Obrador took hundreds of thousands of supporters to the streets in protest when he narrowly lost in 2006. "We hope the candidate of the left will act with democratic maturity and also recognize the results," Mr. Coldwell said.
Ms. Vazquez Mota garnered little more than 23 percent in the exit polls. Mr. Lopez Obrador had about 30 percent of the vote.
The PRI has been bolstered by voter fatigue because of a sluggish economy and the sharp escalation of a drug war that has killed roughly 50,000 Mexicans over six years.
Hugo Rubio, 33, a municipal employee in Nezalhualcoyotl, said he expects "more jobs, more tranquility in terms of security" under Mr. Pena Nieto. "He has demonstrated that [the party] had changed, that he cares about the people who are most in need," Mr. Rubio said at a Pena Nieto rally.
Few problems were reported during the vote, although some polling stations ran out of ballots and at least nine people were arrested in Chiapas for trying to pass ballots premarked for the PRI.
Interior Secretary Alejandro Poire said that across the country, federal forces worked with local and state authorities, as well as election officials, to guard the peace.
Sergio Ortega, 31, a businessman from Guadalajara, said he would vote against Mr. Pena Nieto to try to prevent return of the PRI. "He had too much favoritism. They played many tricks," Mr. Ortega said.
Mr. Pena Nieto cast himself as an economic moderate in the tradition of the last three PRI presidents. He has called for greater private investment in Mexico's state-controlled oil industry, and has said he will try to reduce violence by attacking crimes that hurt ordinary citizens while de-emphasizing the pursuit of drug kingpins.
Mr. Pena Nieto, 45, who is married to a soap opera star, has been dogged by allegations that he overspent his $330 million campaign fund limit and has received favorable coverage from Mexico's television giant, Televisa.