Abortion is, with few exceptions, illegal in Mexico, and a move to make the laws in one state even tighter has turned the issue into a an unwelcome challenge for the National Action Party, or PAN, which on July 2 wrested the presidency from the ruling party for the first time in 71 years.
The abortion question will serve as a measure of whether PAN--which has long relied on militant Roman Catholic supporters--can become a party for the whole nation.
And for President-elect Vicente Fox, who is visiting the United States this week, it presents a test of his efforts to project a modern, forward-looking image.
Mexicans are eager to delve into many issues suppressed during seven decades of basically one-party, paternalistic rule--government crimes, ethnic and social divisions. But when it comes to abortion, most people wish the debate would just go away.
Instead, it started to resurface in April, when PAN officials in the state of Baja California pressured a 14-year-old rape victim to forgo an abortion, forcing her to bear a baby boy. In this case, an abortion would have been legal, but doctors refused to perform it.
Then, early this month, came a bigger political embarrassment for Fox. Lawmakers of his own party in the central state of Guanajuato--a state where Fox was once governor--pushed through legislation to outlaw abortions even for rape victims.
"How do you stop this thing?" PAN secretary general Jorge Oceja pleaded as the controversy spread across the nation.
Suddenly Mexicans are having to re-examine the decades-old system whereby middle-class women can turn to private clinics, while the poor have to risk their health with back-alley abortionists.
Abortion has long been a "don't ask, don't tell" issue that socially liberal governments didn't dare touch.
After centuries of church domination dating back to Spanish colonialism, civil wars in the early 1900s enshrined a secular Mexico. Decades later, many Mexicans, though deeply religious, retain a visceral fear of the church trying to gain political power once again.
The Catholic Church didn't help matters by issuing a stern warning that those who abet abortions can be excommunicated.
But the two latest abortion cases have stung women's groups into protest, and Fox quickly distanced himself from the vote in Guanajuato.
Although he is a churchgoing Catholic and his party has an anti-abortion platform, Fox said, "I want to make it clear this was not a decision by my party." He pledged not to push for any such legislation at the federal level.
"This is unfortunate. We want to get on with issues that can create a consensus in Mexico," said Felipe Calderon, the PAN federal congress leader.
The PAN in Guanajuato, one of Mexico's most conservative states, continues to defend the measure, but has said it might compromise by allowing shorter jail terms for rape victims who have abortions if there are "extenuating circumstances"--if the rapist was a relative or diseased, or if the victim was particularly young or poor.
Each state makes its own laws, but all 31 ban abortion except in cases of rape, danger to the mother, and in some cases, severe birth defects. Doctors caught performing abortions face three to eight years in prison, while their patients can be jailed for up to three years.
The laws are seldom enforced. But simply by being on the books, they keep abortion expensive and clandestine.
How many abortions are performed? The official line, from Health Secretariat spokesman Jose Luis Lopez, is, "This is a practice that is illegal, and thus we don't have statistics on it."
The reality is that "you just ask your friends; everybody knows where to get one, or knows somebody who knows," says Sandra, a 31-year-old Mexico City actress who paid about $600 for an abortion several years ago at a private clinic.
Speaking on condition that her surname be withheld, Sandra said the clinic was in a plush Mexico City high-rise. It provided a full operating room, nurses, an anesthesiologist, and blood-pressure monitor, and the whole procedure took a half-hour. And it was all technically illegal.
The poor would more likely turn to backstreet practitioners who use injections or heavy doses of Zorrilla herb tea to provoke a hemorrhage or kill the fetus, at which point a public clinic must operate to save the woman's life.
Non-governmental groups estimate that up to 800,000 abortions a year are performed here.
Maria Consuelo Mejia of Catholics for the Right to Choose, who led one of the protests triggered by the Guanajuato case, said that for 20 years she has been told that "this just isn't the right time to get into that issue."
"Now it can't be ignored anymore, and maybe that is a good thing," she said
But Fox says the existing law should stay. Instead, he favors adoption, and himself has adopted four children.
"An adopted child can win the hearts of other parents," he says, "and I'm proof of that."