MEXICO CITY (AP) — Mexico’s secretary of the interior said Thursday that attacks that have killed 35 candidates or contenders for nominations and threats to others are largely unrelated to Sunday’s elections.

Olga Sanchez Cordero, Mexico’s top domestic security official, called the violence “isolated incidents” and said they might affect races in less than 10 of Mexico’s over 2,500 municipalities.

She said most of the incidents were related to disputes over land, benefit programs or other community issues. Others may have to do with pressure groups of farmers or workers, or criminal organizations. Sanchez Cordero said “the vast majority have no relation to the elections.”

According to the Etellekt consulting firm, 35 candidates or primary contenders have been killed in Mexico so far this election season.

Most of those killed were running for local posts, like mayor or town council seats. Some were from minor parties who appeared to have little chance of winning. But analysts say drug cartels in Mexico may have attacked some candidates because they threatened to draw votes away from the gangs' favorites.

Experts say criminal gangs often seek to control local government, because that can earn them opportunities to extort money from municipal budgets, identify lucrative kidnap or extortion victims, and gain the support or acquiescence of local police.