Dear student,
elections are held in mexico every six years since its independence in 1930 to elect the president but til 2000, every election was won by a party called PRI or institutional revolutionary party. it was never single party elections, but the ruling party never had a fair chance of losing as under democracy should happen. opposition parties contested, yet for 70 years PRI managed to win due to dirty tricks like last minute shifting of polling booths, rigging of votes and spending large sum of money during the campaigns.
Regards