Updated

Mexicans were voting in local elections in 14 states on Sunday with one key governorship at stake after a campaign marred by violence against candidates.

The governor's seat in Baja California state, held by the conservative National Action Party (PAN) opposition for the past 24 years, was the biggest prize in the regional polls and its result could affect a national reforms pact.

Some 32 million voters were casting ballots in 931 of the country's 2,440 municipalities as well as for candidates in state legislatures in 14 of 32 federal entities.

Soldiers were providing security in several states while the federal attorney general's office deploy some 1,500 agents following a rash of violence that took the lives of at least six candidates, campaign workers and their relatives in recent weeks.

The latest victim was Aquiles Gonzalez, a mayoral campaign manager of the leftist Democratic Revolution Party in the northern state of Zacatecas who was murdered on Friday.

The old ruling Institutional Revolutionary Party (PRI), which reclaimed the presidency in December after a 12-year absence, hopes to triumph in Baja California, home to the vital border town of Tijuana.

President Enrique Pena Nieto made two big promises when he took office: Reducing the level of drug violence that left 70,000 dead during his predecessor's six-year term, and keeping the PRI's old undemocratic ways in the history books.

Pena Nieto struck a Pact for Mexico with the PAN and the PRD that led to the major education and telecommunication reforms, and he hopes to breathe new life into the energy sector and tax system.

But the pact coud be affected by the local election if the PAN loses Baja California, which could weaken the opposition party's leader, Gustavo Madero, whose deal with the PRI has angered a wing of his party.

The opposition has also accused the PRI of returning to its old ways by luring voters with social programs for the local election.

Madero himself said he was unable to vote at his polling station in the northern state of Chihuahua, posting a video on Twitter of the closed location and the message "Morning TRICKS of the PRI."

The PRI has rejected accusations of dirty tricks and countered that the opposition has committed abuses. A PRI candidate in Chihuahua has been among the victims of the campaign season.