MEXICO CITY, Mexico — As campaigners in the gubernatorial race in the Caribbean state of Quintana Roo took to the streets this month, the headquarters of the main leftist candidate were shuttered, vast posters of his smiling face covering an empty building.
The candidate himself, former Cancun mayor Gregorio Sanchez, fondly known as "Greg" by his supporters, was 2,500 miles away on the Pacific coast in a federal prison.
On June 1, a federal judge charged Sanchez with racketeering and drug smuggling charges, saying he worked with the bloodthirsty cartel known as the Zetas — an indictment that bans him from the ballot paper.
The Sanchez case is part of a dark cloud of fallout from the drug war that is causing problems in gubernatorial and mayoral elections across Mexico this year.
In other cases, candidates have been photographed at parties with notorious traffickers, aspirants have dropped out because of narco-threats, and one mayoral candidate was actually gunned down in a brutal killing.
The tensions come in the run up to a "Super Sunday" vote on July 4, in which Mexicans elect 12 of the nation's 31 governors and mayors in another three states.
"The problems created by the drug war could stain elections in a major part of the country," said Francisco Abundis of the polling firm Parametria. "This will be a very bad sign for Mexico's democracy."
A key difficulty is that many of the races are in the very states that have been hardest hit by drug-related violence, including Chihuahua, home to the murder capital Ciudad Juarez, and Sinaloa, the cradle of Mexican cartels.
The Caribbean state of Quintana Roo — where millions of Americans visit the white beaches every year at Cancun and the Mayan Riviera — also has historic ties to trafficking.
It is a straight line across the Caribbean from Colombia's north coast to the peninsula and smugglers take loads of cocaine on the route in speedboats.
In May, former Quintana Roo governor Mario Villanueva was extradited to the United States on cocaine-trafficking charges.
Federal prosecutors allege that Sanchez was following in Villanueva's footsteps, receiving millions of dollars to protect smuggling operations while mayor of Cancun.
The prosecutors say they have evidence that Sanchez made bank withdrawals totaling $2 million, far more than his declared income, and have three protected witnesses who have testified to his corruption.
However, his Democratic Revolution Party (PRD) claims that Sanchez is being framed as part of a political witch hunt to rob them of their popular candidate.
"This is monkey business by federal prosecutors," PRD leader Jesus Ortega said Wednesday. "They are trying to take him out of the race to impose the official candidate. We will not permit this."
Ortega said they are appealing the charges and criticized the protected witnesses.
Sanchez's defense team claimed the witnesses make absurd claims including one that the candidate went to an imaginary "narco-summit" in the resort of Acapulco with leaders of all the major cartels.
In 2009, federal agents arrested 12 mayors in the state of Michoacan on drug charges, many of them PRD, on the basis of protected witnesses. All but two have been released for lack of evidence, feeding claims that that was a dirty maneuver to affect last year's elections.
In Sinaloa state, the staining of a candidate for July's race did not come from federal prosecutors but from the press.
Reforma newspaper published a photograph of gubernatorial candidate Jesus Vizcarra of the Institutional Revolutionary Party (PRI) at a party many years ago with kingpin Ismael "El Mayo" Zambada — who has $5 million U.S. bounty on his head.
Vizacarra retorted that he has no ties to traffickers.
Across the country in Tamaulipas, over the border from Texas, elections for mayors have been marred by daily street shoot-outs between rival cartels that have left hundreds dead.
In May, gunmen in the Tamaulipas town of Valle Hermoso burst into the farm supplies business of Jose Guajardo Varela — candidate for the National Action Party of President Felipe Calderon — and shot him dead along with his son.
In three other towns in the state, National Action says it cannot field candidates because of threats from trafficking gangs.
"If there is fear and violence, there is no freedom. And if there is no freedom we cannot have fair elections," said Maria Eugenia Valdes, a political scientist at the Metropolitan Autonomous University in Mexico City.
Given such problems of violence and corruption, it is likely that many of July's races will end up in the courts, Valdes said.
July's elections comes exactly 10 years after Mexicans voted to end seven decades of one-party rule.
Valdes said the latest tensions show that the nation is still having real problems establishing a multi-party democracy to replace that.
"A new system, a new set of rules, has not been established yet," she said. "Instead we have many parts of the country that are ungovernable."