The western Mexican state of Michoacan is holding elections Sunday amid tight security, with more than 10,000 security forces members, 800 vehicles and 17 aircraft deployed to maintain order.

The approximately 3.4 million voters in President Felipe Calderon's home state are electing a successor to Gov. Leonel Godoy, the mayors of 113 cities and the 40 members of the state legislature.

The state's governorship has been held since 2002 by the leftist Party of the Democratic Revolution, or PRD.

Luisa Maria Calderon, the president's sister, Silvano Aureoles, who is heading the ticket of the alliance forged by the PRD, Convergencia and the Workers Party, and Fausto Vallejo, of the Institutional Revolutionary Party, or PRI, are vying for the governorship.

Calderon, known as "Cocoa" and the candidate of her brother's conservative National Action Party, or PAN, and the New Alliance Party, or PANAL, and Vallejo are the favorites to win the governorship.

Vallejo, the mayor of Morelia, the state capital, is trying to win Michoacan for the PRI and continue the party's streak of victories ahead of the 2012 presidential elections.

The leftist alliance formed by the PRD, Convergencia and the Workers Party is trying to keep Aureoles in power, accusing Calderon, a psychologist, of using federal funds in her campaign.

Michoacan has been a PRD stronghold since 2002, when Lazaro Cardenas Batel, the son of former presidential candidate Cuauhtemoc Cardenas, won the governorship.

Voters will be unable to cast ballots in the city of Cheran because of the lack of security, the state elections office said.

The federal Attorney General's Office deployed 94 agents to the cities of Morelia, Apatzingan, Lazaro Cardenas, Uruapan, Zamora and Zitacuaro to prevent election fraud.

The three gubernatorial candidates concluded their campaigns last Wednesday in the wake of the murder of La Piedad Mayor Ricardo Guzman Romero and the withdrawal of several candidates from mayoral and legislative races due to the drug-related violence in the state, which has been the scene of a turf war between the La Familia Michoacana and Los Caballeros Templarios cartels.

Michoacan was the first state where President Calderon deployed federal security forces shortly after taking office in December 2006 and declaring war on Mexico's drug cartels.

The state has been dealing with a wave of drug-related violence blamed on the break-up of La Familia, which was considered one of Mexico's most powerful drug cartels.

La Familia has been severely weakened in recent months by infighting and government operations targeting the gang.

The cartel began unraveling after the death of one of its top bosses, Nazario Moreno, last year, officials and analysts say.

Moreno, known as "El Chayo" and considered La Familia's ideological leader, was killed in a shootout with the Federal Police in December 2010.

The La Familia faction led by Jesus Mendez, who was arrested in June, has been fighting the group led by Servando Gomez and Enrique Plancarte, who formed the Los Caballeros Templarios cartel in March.

Michoacan, located on the Pacific coast, is used by drug cartels to smuggle drugs from South America into Mexico.

The drugs are then moved via the Pacific corridor or through central Mexico into the United States, the world's largest consumer of illegal drugs.