While some might quibble with Ms. Luna’s technique, few would argue against her appeal to clean up Mexico’s electoral politics. Mexican political campaigns have never been for the faint of heart, and this year has been no different, with rough-and-tumble contests that have made a certain presidential contest north of the border look almost quaint in comparison.

The official campaign period in Mexico, which by law lasted only two months and ended on Wednesday, was marked by “a dirty war,” to use the favored term of the Mexican news media and political class. Candidates all over the country have hurled accusations of corruption at one another, including charges of graft and financing by drug traffickers. In the governor’s race in Veracruz, one candidate even accused his main competitor of being a pedophile.

Some contests also featured violence and intimidation, including the firebombing of a party leader’s office in Veracruz. Dozens of local and regional candidates withdrew from races, reportedly because of threats from drug traffickers.

A lot is at stake. More than 1,300 seats are up for grabs, with the governorships the most important. The outcome of Sunday’s vote could also serve as a prologue for the 2018 presidential election. President Enrique Peña Nieto’s Institutional Revolutionary Party holds nine of the 12 contested governorships, but he is polling lower than any president in the past two decades, and his plummeting popularity could hurt his party’s chances on Sunday.

Luis Carlos Ugalde, the director of Integralia Consultores, a political consultancy in Mexico City, said the level of invective and the prevalence of corruption allegations had increased in recent electoral cycles. This year’s tone was “the most negative” he had seen, he said.