President Andrés Manuel López Obrador, whose party strongly backs the proposal, is expected to sign the bill, sandwiching the U.S. between the world’s two biggest legal marijuana markets.

Why this is a big deal: With a population of nearly 130 million people, Mexico would become the largest country in the world to legalize cannabis at the national level. By comparison, the two other countries that already took that step — Canada (37.6 million) and Uruguay (3.4 million) — have a combined population that adds up to less than a third of Mexico’s.

The specter of legal marijuana markets on the United States’ northern and southern borders is expected to put new pressure on the federal government to loosen restrictions on marijuana.

“My guess is at some point that drives the push to decriminalize or legalize,“ said Andrew Rudman, director of the Mexico Institute at the Wilson Center, pointing out that a majority of U.S. House members now represent states with legal markets. “I think Mexico probably gives more impetus to something that might have happened anyways.”

In December, the U.S. House passed legislation that would end federal penalties for marijuana possession and scrap some past convictions. With Democrats winning control of the Senate in January, the prospects for loosening marijuana restrictions have increased, although most close cannabis policy watchers are still skeptical that there will be a big change in federal policy anytime soon.

Biden’s stance: The president has said that he wants to end criminal penalties and expand medical research regarding marijuana but doesn’t support full legalization. Vice President Kamala Harris was a sponsor of the Senate version of the bill the House passed last session.

Biden has nominated California Attorney General Xavier Becerra — a strong supporter of marijuana legalization — to be his secretary of Health and Human Services. Under Becerra’s leadership, HHS could amend its 2015 stance that said marijuana has no medicinal benefits.

Attorney General Merrick Garland, could play an even more central role in determining federal marijuana policy. Garland argued during a confirmation hearing last month that cracking down on state-legal marijuana markets wouldn’t be a wise use of limited federal resources.

The White House did not respond to a request for comment about whether Mexican legalization would change Biden’s stance.

The background: In November 2015, the Mexican Supreme Court ruled that prohibiting people from using marijuana for personal use was unconstitutional. Two years later, legislation legalizing medical marijuana was signed into law.

Then in October 2018, the Supreme Court ruled that the ban on recreational use of marijuana was unconstitutional and ordered the Legislature to take action. It initially set a deadline of 90 days to implement the decision, but that timeline has been extended multiple times.

However, the Legislature now appears ready to grant final approval. The Chamber of Deputies approved the bill by an overwhelming margin. Since changes were made in the Chamber, the bill now returns to the Senate for another vote.

“Honestly, I don’t expect to see any bad surprises this time around,” said Erick Ponce, president of Grupo Promotor de la Industria del Cannabis, a leading industry group.

The details: The bill would legalize possession of up to 28 grams of marijuana. It would also allow individuals to grow up to six plants.

Forty percent of cultivation licenses for the first five years would be reserved for the communities that have been disproportionately impacted by criminal enforcement, although the details of that would still need to be worked out.

The Chamber of Deputies made changes to the previously passed Senate bill related to which government agency would manage licensing, foreign investment and caps on THC potency in edibles and e-cigarettes.

Who’s opposed to it: Unlike the U.S., where polling shows about two-thirds of Americans support legalization, permitting recreational sales would buck public opinion in Mexico. A poll conducted by El Financiero in July found that 58 percent of Mexicans are opposed to legalization, while just 38 percent support it. The survey also showed a stark generational and educational divide on the issue. Older respondents and those without a high school degree were far more likely to oppose legalization.

Mexico’s Roman Catholic Church has been among the staunchest critics of legalization. After the Senate passed the legalization bill in November, the Mexican Bishops Council blasted the legislation.

“The bill that was approved does not address the health damages that arise from an ever increasing use of marijuana, does not address the effects on families due to young people’s consumption of drugs, and does not contribute to reducing and inhibiting exposure to drugs,” the council wrote.

What’s next: Proponents of the bill expect the Senate to vote early next week. If passed, it will head to the president’s desk.

Recreational marijuana sales would not begin immediately if the bill becomes law. It would take time for regulations to be written and businesses to get licensed. The country’s medical program is just getting off the ground more than two years after legalization was passed.