Argentine President Alberto Fernandez will fulfil an election pledge next week when he brings a bill before Congress aiming to legalise abortion, setting off the latest salvos in a debate that has bitterly divided the traditionally Catholic South American nation.

Thousands of women sporting the green scarves that have become synonymous with the campaign for legalised abortion plan to descend on the streets of Buenos Aires in a bid to ensure the leftist leader keeps his promise.

Likewise, anti-abortion campaigners, including Catholics and Evangelicals, plan to demonstrate waving blue handkerchiefs to ensure the practise remains illegal.

Mass pro-abortion rallies brought Buenos Aires to a standstill in 2018 – when abortion was last debated in the Congress – but was not enough to sway the conservative Senate, which rejected the bill after it had been passed by the lower house.

But campaigners believe this time they have political momentum in their favour, and they made a show of force in their thousands two weeks ago with another rally outside Congress.

“Having a president who speaks in favour is a boost for all of us,” Victoria Tesoriero, of the National Campaign for the Right to Abortion, said.

“We understand that it’s a historic moment and we have to stay organized on the street,” she said.

Fernandez was blunt about legalising abortion in comments last weekend.

“Abortion happens. It is a fact. In the 21st Century every society needs to respect the individual decision of its members to freely do what they want with their bodies,” he said.

Argentina has pioneered gay marriage and gender identity legislation in Latin America. If abortion is also approved, it would become only the fourth Latin American state to do so after Cuba, Uruguay and Guyana -- though it is also allowed in Mexico City and the Mexican state of Oaxaca.

Several Central American countries ban the practise altogether.

Latin American abortion activists were dealt a setback this week when the Constitutional Court in Colombia decided to keep in place the usual restrictions against abortion when ruling on a case brought by an anti-abortion activist who wanted a total ban in all instances.

The usual exceptions apply under Colombian law, common across Latin America: cases of rape, when the fetus has serious health problems likely to affect its survival, or when there is a risk to the life of the mother.

Only two of those exceptions exist in Argentina, rape and maternal risk.

Outside of those exceptions, abortion remains a crime in Colombia, Argentina, and most other countries – punishable by up to four and a half years in prison.

In Argentina, Fernandez’s position is steadfastly opposed by anti-abortion activists backed by the still-powerful Catholic Church.

The debate has fiercely divided Argentine society.

“The active militancy of the president worries us because we believe he will do everything possible to get this done,” says Camila Duro, spokeswoman for the anti-abortion Young Front movement.

“We want to alert the political powers that be that there is a majority in the country, that goes out to vote and goes out on the streets, that does not agree with this bill to discard Argentines,” she said.

Long a bastion of the Roman Catholic Church, Argentina is the homeland of Pope Francis, a former Archbishop of Buenos Aires. But public attitudes towards religious belief have changed in the country.

The latest survey shows a doubling in the proportion of the population who believe a woman has a right to abortion. In 2008, that figure was 14 per cent, in 2019 it had grown to more than 27 per cent.

Hoping to form a sea of bandanas in the centre of Buenos Aires, the pro-abortion activists are planning a major demonstration outside Congress next Monday.

“We are in a new stage of feminism, both in the country and throughout the region,” said Tesoriero.

Catholic bishops have other ideas.

On Sunday, they will hold a concelebrated mass at the Lujan basilica, 75km from Buenos Aires, to mark International Women’s Day with the slogan: “Yes to Women, Yes to Life”.

Despite the Church’s best efforts, abortion campaigners believe the political groundswell is with them and that Argentina will soon become the most populous Latin American nation to legalize the practice.

They point to around 400,000 abortions carried out every year, mostly in clandestine conditions marked by poor hygiene for the 37 per cent of the population living below the poverty line.

For the women who can afford it, private clinics are available for around $1,000.