Argentine lawmakers face a crucial vote on Wednesday to decide whether or not to legalise abortion amid fiercely polarised campaigns for and against the proposed bill.
Last week the Senate approved the text for the bill that was originally passed by Congress's lower house in June by the narrowest of margins.
This time, though, it is widely expected to fall short of the votes necessary to pass into law, with 37 of the 72 senators said to be ready to say no despite a massive social campaign to have it adopted.
But despite projections and strong opposition from the highly influential Catholic Church in the homeland of Pope Francis, campaigners are not giving up hope.
"We're doing everything so that the initiative passes. We have faith in the street movement," leading campaigner Julia Martino told AFP.
"We believe many senators will show their support when the vote happens."
Currently, abortion is allowed in Argentina in only three cases, similar to most of Latin America: rape, a threat to the mother's life or if the fetus is disabled.
If passed, the bill would legalise abortion during the first 14 weeks of pregnancy and see Argentina join Uruguay and Cuba as the only countries in the region to fully decriminalize it.
It's also legal in Mexico City while only in the Central American trio of El Salvador, Honduras and Nicaragua does it remain totally banned.
With the tide seemingly flowing against legalisation, pro-abortion groups tried to amend the bill to reduce from 14 to 12 weeks the period in which it would be permitted, but that move failed.
What activists can count on, though, is huge support from citizens.
In preparation for the big day, protesters wearing their now symbolic green scarves began a vigil at midnight in front of Congress, due to last until the announcement of the vote result.
QUESTION OF RIGHTS
Other demonstrations will take place around the world in front of Argentine diplomatic missions.
"There are things that come about at the last moment, like what happened in the House of Deputies," added Martino.
In mid-June, the lower house voted in favour by just 129 to 125 thanks in part to the nonetheless pro-life liberal President Mauricio Macri's insistence in pushing the bill through parliament.
Pro-abortionists insist this is a question of social justice, public health and women's rights.
Last month, campaigner Elsa Schvartzman told AFP the movement aimed to end "avoidable deaths of women."
"We're talking about the right to live in dignity, with autonomy, to be able to choose freely," added the 67-year-old mother of three.
Senator Norma Durango from the Justice Party said she would work "until the last minute so that this becomes law," warning that those who vote against the bill would be "responsible for continuing deaths."
Various charities have estimated that 500,000 illegal, secret abortions are carried out every year in Argentina, resulting in around 100 deaths.
But the anti-abortionists are not lacking support and planning their own demonstrations under the banner: "Let's save both lives."
Priests and nuns have been joined by Jewish rabbis, Muslim imams and other Christian churches to oppose the bill.
The Catholic Church even appointed a bishop, Alberto Bochatey, to handle dialogue with Congress on the issue.
Last month, Bochatey, 62, told AFP that "you cannot make a law to justify the elimination of human life," but said the Church is against penal detention as a sanction for those carrying out illegal abortions.
Opponents, though, are angry about what they see as Church interference in what should be secular affairs.
"Only a secular state can guarantee rights," said Schvartzman, adding that one of activists' demands is an "effectively secular state."