Mexican judges on Wednesday overturned the result of the Nov. 13 mayoral ballot in Morelia, capital of the western state of Michoacan, citing violations of campaign law by the winner’s party.

The 2-1 ruling by a regional panel of the TEPJF electoral court emerged from a session that began Tuesday night and stretched into the wee hours of the morning.

Wilfrido Lazaro, the candidate of Mexico’s main opposition Institutional Revolutionary Party, or PRI, won the Morelia mayor’s race over Marko Cortes, standard-bearer of the conservative PAN, which has been in power at the national level since 2000.