The election of Delfina Gómez as governor of Mexico state signals the decline of the Institutional Revolutionary Party (PRI), which has dominated politics in the region for almost a century.
The PRI's candidate, Alejandra del Moral Vela, was beaten by eight points by Gómez, a former school teacher and ally of the populist president Andrés Manuel López Obrador.
The win for Gómez and Morena, the party founded by López Obrador, marks an impressive victory and an end to the PRI's powerful network that has controlled politics in the region for years.
The PRI has lost every other state and the presidency in recent years.
The outgoing governor, Alfredo del Mazo Maza, secured a narrow victory in 2017 amid widespread allegations of fraud.
The defeat of the PRI could prove to be "insurmountable" when it comes to contesting the presidential elections next year, according to the political analyst Gabriel Corona Armenta.
The win for Gómez and Morena, the party founded by López Obrador, marks an impressive victory and an end to the PRI's powerful network that has controlled politics in the region for years.
The PRI has lost every other state and the presidency in recent years.
The outgoing governor, Alfredo del Mazo Maza, secured a narrow victory in 2017 amid widespread allegations of fraud.
The defeat of the PRI could prove to be "insurmountable" when it comes to contesting the presidential elections next year, according to the political analyst Gabriel Corona Armenta.