A candidate for a seat in the Guerrero state legislature was gunned down Monday at his house, Mexican prosecutors said.

Margarito Genchi Casiano, a member of the leftist Party of the Democratic Revolution, or PRD, was killed around 7:00 a.m., the Guerrero Attorney General's Office said.

The politician was murdered by several gunmen who went to his house in Llano Largo, a community on Guerrero's Costa Chica.

Genchi Casiano's body was taken to the Pacific resort city of Acapulco, where an autopsy will be conducted, the AG's office said.

Investigators have not determined the motive for the murder, which comes as the campaign for the July 1 general elections enters the home stretch.

Mexico's presidential campaign ends on June 27, four days before some 80 million voters head to the polls to cast ballots for a new president, 628 legislators and thousands of other officials.

Genchi Casiano served as mayor of the city of Florencio Villareal from 2005 to 2008. He was also head of the union that represents beverage workers in Guerrero, a state in southern Mexico.

The drug-related violence in several states has been viewed as a challenge for the electoral process since the campaign for the general elections officially started on March 30.

Guerrero Gov. Angel Aguirre Rivero launched a security operation last year with the support of the federal government to step up security in the southern state.

"Operation Safe Guerrero" was launched on Oct. 6, 2011, in an effort to reduce the soaring crime rate in the region.

Acapulco, a favorite among Mexican and foreign tourists for decades, has lost business to other destinations due to the violence.

President Felipe Calderon made an appearance in the Pacific resort city on May 30 to officially launch a new crime-fighting plan. EFE