ATLIXCO, Mexico (Reuters) - Sex sells - at least that's what the ruling party candidate is hoping as she seeks to rescue her fading chances in Mexico's upcoming presidential election.

Sitting well behind the frontrunner, Josefina Vazquez Mota of the National Action Party (PAN) has appealed to women voters to use their wiles to ensure their husbands vote on July 1.

First she urged them on her Twitter account to withhold "cuchi cuchi", or hanky panky, for a month if the husbands don't vote. Then, challenged by a disgruntled man, she upped the ante on Monday.

"Today a man wrote to me and said: Josefina, why the negative? What's the prize? Why not a month without hanky panky for those who don't come out to vote, and double rations for those who do?" the conservative, usually serious Vazquez Mota told a rally in the city of Atlixco, in the state of Puebla.

"If the woman wants to, that depends on each individual. But the thing here is we all take part (in the vote)," she added.

Support for the conservative PAN has been hurt by a mounting death toll in the government's war on drug cartels, and a failure to create enough jobs for the growing population.

Most polls place Vazquez Mota in third in the race, well over 10 points behind front-runner Enrique Pena Nieto of the opposition Institutional Revolutionary Party (PRI).