By Mica Rosenberg and Ana Isabel Martinez
VERACRUZ, Mexico (Reuters) - The main opposition political party is at the root of the violence engulfing Mexico, ruling party presidential candidate Josefina Vazquez Mota said after one of the worst atrocities in the country's drug war.
Fighting to close a big gap with Enrique Pena Nieto, the front-runner for the July 1 election, Vazquez Mota sharpened her attacks on his Institutional Revolutionary Party, or PRI, saying it had made life easy for brutal drug traffickers in Mexico.
Support for her conservative National Action Party (PAN) has been eroded by the rising tide of brutality that has swept across Mexico since President Felipe Calderon sent in the army to fight drug gangs soon after taking office in December 2006.
In an interview late on Sunday after 49 decapitated bodies were found on a highway outside the northern city of Monterrey, Vazquez Mota said the origins of Mexico's violence can be traced to years of neglect or collusion during decades of PRI rule.
"Seven out of 10 murders committed by organized crime happen in states governed by the PRI, which is an unequivocal sign that there has been omission, indifference and complicity that must be proven by the proper authorities," she told Reuters.
The PRI, which governs nearly two thirds of Mexico's 31 states, including Nuevo Leon where the latest massacre occurred, says the government's strategy has failed.
But Vazquez Mota continues to defend the army-led offensive begun by Calderon, who cannot seek re-election.
"I think President Calderon has taken on the cartels with great courage and resolve and is trying to reverse what was permitted for many years," she said during a campaign stop in Veracruz state on Mexico's Gulf coast. "Today many major capos and criminals are in jail that for many years walked free and had the space to advance and take control of territory."
Vazquez Mota, who hopes to become Mexico's first woman president, may have undermined her campaign with such unquestioning support of Calderon's drug war strategy.
She lags the PRI's Pena Nieto by about 20 percentage points, and recent polls have shown her slipping into third place behind leftist hopeful Andres Manuel Lopez Obrador.
More than half of Mexicans believe the criminals are winning the drug war, a survey showed late last year.
The murders over the weekend brought the death toll of people killed this past week to nearly 100. Bodies have been hung from bridges, stuffed in ice boxes or cut up in plastic bags in an escalation of attacks between rival cartels.
There have been more than 50,000 drug-related murders during Calderon's administration.
The government has trumpeted the capture or killing of many of the drug kingpins on its most wanted list during Calderon's term, but some experts say taking out cartel leaders has only fanned infighting and inflamed violence.
The view from Vazquez Mota's Veracruz hotel room in an upscale shopping mall overlooked the intersection where last September drug cartels dumped more than two dozen bodies in morning traffic, causing panic in the port city.
The federal government sent in marines after the attacks, and pickup trucks full of masked soldiers with automatic weapons now patrol the city, inspecting suspicious vehicles.
People have returned to the plazas and seaside boardwalk and streets are bustling again with vendors and musicians at night.
But just two weeks ago, three local journalists were killed in a haunting reminder that violence has not disappeared from the state.
Vazquez Mota proposes the creation of a militarized national police with at least 150,000 officers, tougher controls on money laundering and stiffer penalties for corrupt officials.
Congress blocked similar efforts by Calderon to form a national police force to replace hundreds of poorly equipped municipal and state officers often vulnerable to graft.
Instead the federal government mandated all local police forces go through background checks and fold their ranks into a single command structure headed by the states. Many local governments have not yet complied.
Vazquez Mota swiped at Veracruz's PRI governor, Javier Duarte, without directly mentioning his name, at a rally packed with women supporters in a downtown cultural center on Sunday.
"The local governors have lied to the families of Veracruz because here they didn't certify the police, here they opened the door to organized crime," she said. Her promise to keep the marines on the streets until local police can control crime prompted a standing ovation from the well-dressed crowd.
Vazquez Mota also pointed to examples of former party governors accused of corruption or who had made statements in the past about cutting deals with cartels.
The former treasurer in the northern state of Coahuila is wanted in the United States for money laundering, raising questions about the administration of ex-governor Humberto Moreira, who later served as PRI chairman, she said.
The PRI, which ruled Mexico for more than 70, lost the presidency to the PAN in 2000.
Pena Nieto, a former governor of the State of Mexico, is not proposing a radical departure from Calderon's anti-drug strategy and also wants a new military police force.
Only Lopez Obrador, who narrowly lost to Calderon in 2006, has proposed a timetable to pull the army off the streets.
(Editing by Dave Graham and Christopher Wilson)