BUENOS AIRES — Lucía Bulat, a 19-year-old medical student, was dancing on the steps of the congressional palace in Buenos Aires as she looked out on a crowd of abortion rights demonstrators who had gathered in Argentina’s capital.

“It’s a beautiful day,” Ms. Bulat said on Tuesday. “We’re empowering ourselves and demanding our rights. We can’t let people keep telling us what we can and cannot do with our own bodies.”

Not long ago, abortion rights activists in Argentina had little reason to believe they could make the polarizing issue a legislative priority.

But lawmakers in Pope Francis’ homeland began considering legislation this past week that would allow women to have an abortion in the first 14 weeks of pregnancy.