By Laura Smith-Spark, CNN
(CNN) — The French Senate will debate a controversial bill Thursday that would extend the right to marry and adopt to same-sex couples.
The lower house has already approved the legislation, in the face of protests from those opposed to the measure.
If it passes the Senate, it would mark the biggest step forward for French gay rights advocates in more than a decade.
Extending the right to marry and adopt to same-sex couples in France was one of President Francois Hollande’s electoral pledges in campaigning last year.
The left, which includes Hollande’s governing Socialist Party, dominates the National Assembly, where the bill passed by a large majority in February. The party has only a slim majority in the Senate.
The legislation has won wide backing from gay rights advocates.
But the plan faces stiff opposition from the Roman Catholic Church, other religious groups and social conservatives, with huge numbers turning out for protest marches in Paris in recent weeks.
The most recent, held less than two weeks ago, was attended by some 300,000 people, Paris police told CNN affiliate BFM-TV.
France is not the only nation currently wrestling with the polarizing issue.
Uruguayan senators voted overwhelmingly in favor of a same-sex marriage measure Tuesday, despite vocal opposition from the Catholic Church. Next week, lawmakers in the lower house are expected to vote on the senate’s version.
Legislators in the United Kingdom are also weighing proposals to legalize same-sex marriage.
In the United States, the question of same-sex marriage went before the Supreme Court last week, and justices are now deliberating over the matter.
The first same-sex couples walked down the aisle in the Netherlands in 2001. Since then, almost a dozen countries have passed laws allowing same-sex marriages and domestic partnerships, including Canada, South Africa, Belgium and Spain.
In Argentina, the push to legalize same-sex marriage met with fierce opposition from the Roman Catholic Church, with Cardinal Jorge Mario Bergoglio — then the archbishop of Buenos Aires and now the pope — engaging in a notorious war of words with the government over the issue. It was approved in 2010.
The issue has also divided Australia, where lawmakers voted against a bill to legalize same-sex marriage last September. A poll for the advocacy group Australian Marriage Equality indicated that 64% of those surveyed “support marriage equality.”
A law legalizing civil unions was introduced in 1999 in France under a previous Socialist government.
Known in France as the PACS (pacte civil de solidarite), the civil union agreement can be entered into by gay or straight couples and confers many but not all of the rights of marriage.