Buenos Aires, Argentina (CNN) Thousands of people flooded the streets around Argentina's Congress on Wednesday as lawmakers inside were locked in a tense debate over whether to relax the nation's highly restrictive abortion laws.

The Chamber of Deputies began debating Wednesday over a legislation that would legalize elective abortion in the first 14 weeks of pregnancy. That's a huge difference from existing laws, under which women can be imprisoned up to four years for having the procedure.

Lawmakers are expected to vote on Thursday and if the bill passes, it would move to the upper house, the more conservative Senate.

The debate has drawn political activists from both sides of the issue as well as many Argentinians who say they have never taken part in any cause before this one.

Eliana, a 40-year-old baker, joined protesters for the first time on Wednesday because she was forced to break the law in the past.

"I had an abortion when I was 18," she said, refusing to give her last name because the practice is illegal. "I was drunk and was forced into non-consensual sex with someone I had known since I was 10."

When Eliana wanted to get a legal abortion, a lawyer told her a judge would never approve the practice because she knew her rapist.

"Luckily I had enough money and contacts to go to a private doctor's office and everything was done safely," she said. "But what about all the girls who can't do that? What about those who are afraid to tell anyone and don't have enough money to pay a doctor? That's why I'm here."

Lawmakers debate bill

The debate has changed at least one mind inside Congress. Lawmaker José Ignacio De Mendiguren tweeted that he was a Catholic but that "I will vote in favor of the law. My convictions are my own, they guide my life. But my convictions are not the truth."

People demonstrate against the decriminalization of abortion in front of the Cathedral of Tucuman, in northern Argentina, after marching under the slogan "Save Both Lives", on June 10.

Fellow legislator Gabriela Burgos said the bill really doesn't change policy.

"The only thing it promotes is death, there's no way around it," he said. "They talk about the thousands and thousands of lives they're going to save. What about the thousands and thousands that won't even be able to begin?"

Mario Negri, who leads the Macri's Cambiemos (Let's Change) coalition in the lower house, said he received threats after announcing he would vote in favor of the bill. "A true Catholic doesn't threaten nor wishes ill," he wrote on Twitter. "I don't support abortion, I only think that the criminalization of women has failed."

The legislation in the Chamber of Deputies also would allow women to get a legal abortion after 14 weeks if the pregnancy resulted from rape, the woman's health is at risk, or the fetus suffered severe conditions not compatible with life outside of the womb.

President Mauricio Macri has said he's personally opposed to abortion but will sign the bill if it passes.

Protesters in the plaza

Green has become the color of upporters of legalized abortion.

The square outside Argentina's Congress was divided by fences Wednesday, with a large group of pro-legalization protesters beating drums and chanting.

Sofia Sierra, a 19-year-old student, arrived wearing a green handkerchief on her neck. Green is the color of the pro-choice movement in Argentina.

"This is an issue that affects us all as women, regardless of political leanings," said Sierra, who came to the plaza before work at a law firm and planned to return later. "It's about saving women's lives."

On the other side of the square, a group of anti-choice protesters began cheering when a live sonogram of a woman who is 15 weeks pregnant -- one more week than the law would allow -- was broadcast on a big screen. They could also heard the sound of a heartbeat through speakers.

"I dare anyone to tell me that isn't a life," said Ruth Fumaneri, a 26-year-old lawyer from the Campana, Buenos Aires province. "I'm confident lawmakers will do the right thing and vote down this bill."

Mercedes Foletto, 62, who was wearing a light blue handkerchief, the color of the anti-abortion campaign, said she was there to be the "voice of the those who can't speak."

"They can call them fetuses, embryos, whatever they want but the truth is that they are babies. They want to kill babies," she said.

For Lorena Giménez, 39, a pediatric nurse, the debate highlighted the need to strengthen health policies across the country. But she insists that the bill currently under debate in Congress isn't the answer.

"There's a lot of things people don't realize about the bill. A 13-year-old will be able to go get an abortion and doctors will be penalized if they refuse to perform it," Giménez said. "We have to value life, this bill treats life as if it were disposable."

Tough laws

A girl takes part in a march supporting abortion rights in Buenos Aires on June 4.

Argentina is a Catholic country and the homeland of Pope Francis. But supporters of the proposed legislation are heartened by a recent vote in Ireland, another predominantly Catholic country. Irish voters in May approved an amendment to the country's constitution that would allow the repeal of the country's almost total ban on abortion.

"With the vote in Congress, Argentina can join the global trend toward expanding legal grounds to allow abortion and affirming the rights and dignity of women and girls," said José Miguel Vivanco, Americas director at Human Rights Watch.

The #NiUnaMenos, or "not one less," movement thrust abortion rights fully into the public forum.

In 2016, women took to the streets in anger after a 16-year-old girl was abducted outside her school , drugged, repeatedly raped and killed. The movement broadened to include issues such as LGBTQ rights and abortion rights.

"What was once taboo only a few years ago is now being openly and thoroughly debated across society," Giselle Carino, the regional director for the International Planned Parenthood Federation/Western Hemisphere Region, said in an email interview with CNN. Carino said the trend toward legalizing abortion will continue to grow.

But physicians are often hesitant to perform an abortion, even when it's legally sanctioned, Carino said. She said the laws are usually enforced against poor women, since women of means find ways to terminate their pregnancies with misoprostol, an abortion pill, or by going to a private clinic.

Supporters of the bill emphasize that legalization would reduce the number of poor women who try to end their pregnancies through cheap, unsafe methods.

Will it pass?

Giménez and Foletto, the protesters against the bill, are confident it will fail in the Chamber of Deputies. But analysts aren't so sure.

"Considering the way the issue has evolved over the last few weeks and months, it seems a lot more likely that it would be approved than it seemed just a few weeks ago," said Mariel Fornoni, director of Management and Fit, a political consultancy. "There is a lot of social pressure and some lawmakers, particularly the young ones, may be worried that this vote will mark them for future generations."

Polls have consistently shown that a majority of Argentines favor the legalization of abortion and that there is a clear generational divide.

Yet even if approved, there is no guarantee the bill will become law, said Lucas Romero, the head of Synopsis, another consultancy.

"The situation in the Senate is even more complex because, historically speaking, it has a more conservative tendency," Romero said, noting that preliminary surveys have shown a clear rejection of the measure by a majority of senators.

"Of course we can't dismiss the role of public opinion and the pressure that approval in the lower house could bring. Those could both be factors that could change the scenario in the Senate ... but for now it remains very uncertain."