MEXICO CITY Mexico City Mayor Claudia Sheinbaum said on Monday she will step down this Friday to seek the ruling party's presidential nomination, bidding to become the country's first female leader in an election due to be held next year.

President Andres Manuel Lopez Obrador's leftist National Regeneration Movement (MORENA) said on Sunday it would on Sept. 6 announce the winning candidate from its internal selection process. Sheinbaum is one of the favorites.

Most opinion polls have tended to give Sheinbaum a slight advantage in the race for the nomination over her rival Marcelo Ebrard, who said he was standing down as foreign minister earlier on Monday to compete in the contest.

MORENA is heavily favored to win the June 2024 presidential election, lifted by Lopez Obrador's personal popularity.

The 60-year-old Sheinbaum underlined her credentials as a scientist and environmentalist in a speech she gave to announce her resignation. At the weekend, MORENA's leadership agreed that the contenders should step down this week to compete.

"It's the time for women," Sheinbaum said, pledging to continue Lopez Obrador's so-called 'transformation' of Mexico.

Ebrard, who announced his plan to resign last week, had argued that prospective candidates should leave their posts to ensure a level playing field. Interior Minister Adan Augusto Lopez, another contender, is also expected to resign.

Lopez Obrador cannot seek re-election because Mexican presidents are restricted to a single six-year term by law.

(Reporting by Dave Graham; Writing by Sarah Morland)