Two women will compete for the Mexican presidency for the first time next year after the ruling party on Wednesday named former Mexico City mayor Claudia Sheinbaum as its candidate.

Sheinbaum, a 61-year-old scientist by training, will face Xochitl Galvez, an outspoken businesswoman and senator with Indigenous roots selected to represent an opposition coalition, the Broad Front for Mexico.

One of the two in all likelihood will become Mexico's first woman president, and both have invoked cracking the glass ceiling in a nation seeking to shake off a tradition of machismo -- or sexism.

President Andres Manuel Lopez Obrador's Morena party announced that Sheinbaum had won an internal contest to run in the June 2024 election, beating rivals including former foreign minister Marcelo Ebrard.

"Today democracy won," Sheinbaum said, adding: "There will be a woman president of the republic!"

Sheinbaum is a staunch supporter and confidant of Lopez Obrador, a leftwing populist who enjoys an approval rating of more than 60 percent but is required by the constitution to leave office after a single six-year term.

"Sheinbaum is probably the greatest ally in the political history of Lopez Obrador," said analyst Pablo Majluf.

A student leader in the 1980s, Sheinbaum served as Mexico City environment secretary when Lopez Obrador was mayor from 2000-2005.

She was a spokesperson for Lopez Obrador during his failed 2006 election bid, and served as Mexico City mayor herself from 2018 until earlier this year when she stepped down to run for president.

"Girls see an example in me," Sheinbaum told the magazine Gatopardo.

"Being the first woman president would be historic in our country," she added.

In another sign of shifting winds, Mexico's Supreme Court Wednesday decriminalized abortion across the country, ruling that a legal system that penalizes abortion "violates the human rights of women."

Both Morena and the opposition bloc opted to use public opinion polling to pick their nominees.

Hours before the ruling party announcement, Sheinbaum's rival Ebrard denounced what he called "important irregularities" in Morena's polling process and called for a rerun.

The former top diplomat was noticeably absent at the announcement of the results.

- 'Ovaries needed' -

Sheinbaum, the granddaughter of Bulgarian and Lithuanian Jewish migrants, is known for her reserved, cautious style and has vowed to continue Lopez Obrador's policy agenda.

"Having a scientific profile... she tends to surround herself with people who know how to design public policies," Majluf said.

Like Lopez Obrador, Sheinbaum portrays herself as a defender of the poor, including Indigenous communities.

The entry of Galvez -- born to an Indigenous Otomi father and mixed-race mother -- has already shaken up the presidential race.

Her first name means "flower" in the Nahuatl Indigenous language, and her background sets her apart from the traditional conservative opposition.

She wears Indigenous clothing, uses colloquial language peppered with swear words and is known for traveling around Mexico City by bicycle.

The opposition coalition is made up of the Institutional Revolutionary Party -- which ruled the country for more than 70 years until 2000 -- the conservative National Action Party and the leftist Party of the Democratic Revolution.

Galvez, a 60-year-old computer engineer, has criticized Lopez Obrador's security strategy and said that "ovaries are needed" to confront organized crime.

Sheinbaum in contrast "wants to continue doing the same" as Lopez Obrador, Galvez said in an interview with AFP on Monday, pledging a new approach.

"I don't want to keep betting on fossil fuels. I don't want to keep betting on the militarization of the country. I don't want to keep betting on a collapsed health system," she said.

"With me, there will be no going back on the rights won by both the LGBTQ community and women," Galvez vowed.

But she faces an uphill battle given the popularity of Morena.

In a survey published on August 28 by the Reforma newspaper, 46 percent of respondents said they would vote for Sheinbaum in a two-way contest, compared with 31 percent for Galvez.