When Mexico's governing party unveiled the winner of its poll to pick a Mexico City mayoral candidate, the result was clear - but the male victor quickly had to give way to female runner-up Clara Brugada to meet new gender parity rules now reshaping Mexican politics. Last weekend's leapfrogging of the most popular contender in the National Regeneration Movement (MORENA), Omar Garcia Harfuch, was one of the clearest illustrations yet of the challenges Mexico faces enacting rules that mandate equal candidacies for women across thousands of top political jobs. Mexico's national electoral authority INE last month resolved that all political parties must nominate at least five women to compete for the nine elections next year to head regional governments, including the capital Mexico City - part of a decades-long push for greater representation that has led to dramatic results in the socially conservative country.