Mexico's government has moved about 40,000 federal police, soldiers and marines into Oaxaca, Chiapas, Guerrero and Michoacan states ahead of Sunday's vote. National Security Commissioner Monte Alejandro Rubido said the operation to dispatch federal police had started on Friday.

Mexicans in 16 states and the federal district are to vote in the country's biggest midterm election in history. They will select 500 representatives of the lower house of congress, nine governors, more than 300 mayors, and thousands more local office holders.

Professor Mohamed Otaqui Toledo, spokesman for the National Union of Education Workers (SNTE), said the union was taking action against political parties which had approved educational reform, including privatization. "There would be no more public education and it wouldn't be free or mandatory," he told local television.

"The slogan is to boycott the electoral process, as a measure to pressure that our demands be heard. If we don't see advances in this sense, we will have to call for a massive national strike," Otaqui Toledo added.

A splinter teachers' union and other activist groups have in recent days burned ballots and attacked the offices of local political parties.

Recent opinion polls suggest the ruling Institutional Revolutionary Party (PRI) will take about one-third of the vote. This would allow it to maintain its current majority in Congress and pass legislation with the help of smaller parties.

The right-wing, opposition National Action Party (PAN), which was in power for the previous two presidential terms, is expected to take a quarter of the vote. The leftist PRD is expected to come third with about 14 percent of the vote.

Corruption

According to a recent poll, security and justice were the second biggest concerns for voters after the economy, including the linked problems of insecurity, corruption, drug trafficking and addiction.

Long a problem in the country, corruption has for the first time become a political discussion point in an election. "The main topics in Mexican elections tend to be the economy and security," according to Francisco Abundis, director of the polling firm Parametría in Mexico City. "But we've never before seen the issue of political corruption feature so prominently."

"Corruption is a chronic condition in Mexico that has afflicted all of the main parties, it is a structural issue that isn't being addressed," Ríos Piter, former PRD candidate for governor in the central state of Guerrero said.

In January Piter withdrew his candidacy in the aftermath of the disappearance of 43 students in Guerrero, allegedly ordered by the PRD mayor of Iguala, José Luis Abarca Velázquez and his wife. The mass kidnapping and suspected murder of the students became the biggest political and security scandal Mexican President Enrique Peña Nieto had faced during his administration.

In the northern state of Sonora, incumbent governor and PAN party member Javier Gandara faces claims of tax evasion linked to his alleged ownership of nine homes in the United States, including a San Diego mansion. He is under investigation over the disappearance of millions of pesos of national funds.

His opponent for the Sonora governorship, PRI Senator Claudia Pavlovich Arellano, has been accused by opponents of embezzlement, extortion and bribery in the campaign. It is alleged she rented a plane with taxpayers' money to go shopping in Las Vegas and embezzled government funds at a nursery school during her time as a local deputy.

jm/bk (Reuters, EFE)