Argentina's Senate is set to vote Wednesday on a bill that would legalize elective abortion in the predominantly Catholic country, homeland of Pope Francis.

The bill, which has fuelled contentious debate in Argentina, would expand abortion rights to allow women to end a pregnancy in the first 14 weeks. Current laws allow the procedure only in cases of rape, or when the mother’s health is at risk.

The legislation faces a razor-edge vote in Argentina’s more conservative Senate after it was narrowly passed by the lower house of Congress in June. And it has lost some momentum after an opposition senator withdrew her support over the weekend.

Abortion rights activists say the bill’s approval would be a watershed moment for Latin America, where more than 97 percent of women of reproductive age live in countries with restrictive abortion laws, according to the Guttmacher Institute, a think tank focused on reproductive rights. If passed, Argentina would become only the fourth country in Latin America to broadly legalize abortion, after Uruguay, Cuba and Guyana.

But the bill faces stiff opposition.

While Pope Francis hasn’t addressed the legislation directly, he did speak out strongly against abortion just days after the bill was approved by the lower house — comparing abortion to avoid birth defects to Nazi eugenics. The pontiff also issued a letter in March, as the abortion debate began, urging Argentines to “make a contribution in defense of life and justice.”

“Abortion is the ultimate red line for the church,” Celia Szusterman, trustee of the UK board of Pro-Mujer and director of the Latin America program at the Institute for Statecraft, told CNN. “It’s clear that, for the Pope, it would be a personal humiliation if his home country, Argentina, votes in favour of decriminalization.”

Since the Pope’s comments, abortion opponents have pushed back against the bill, with thousands rallying in rural areas of the country and in the streets of Buenos Aires, wearing blue bandannas emblazoned with the slogan “Save both lives.”

“The ones behind the pro-abortion campaign are people who have economic power, particularly in Buenos Aires,” Camila Duro, member of nongovernmental organization Frente Joven, part of the “Let’s save both lives” campaign, told CNN. “They don’t have the support of the majority of the country.”

According to the Argentine Health Ministry’s official statistics, 43 of the 245 recorded deaths of pregnant women and girls in 2016 were due to abortion – making it the number one cause of maternal deaths in the country. But the number could be under-reported because abortion is illegal, leaving some women to resort to dangerous methods of ending pregnancies.

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