Soledad Acuña has formally announced her withdrawal from the race to be the next mayor of Buenos Aires City.
Acuña, 48, confirmed her decision in a video post on social networks.
The decision helps thin out what is already a packed race for the mayorship of the nation's capital, which includes at least two other hopefuls from PRO, the party from which Acuña hails.
Among the hopefuls for the mayoral post, which will be vacated by Horacio Rodríguez Larreta in December, are City government ministers Fernán Quirós and Jorge Macri.
UCR Senator Martín Lousteau, whose party forms part of the Juntos por el Cambio coalition from which PRO also hails, is also one of the leading candidates.
Analysts had previously anticipated Acuña's withdrawal, considering that she lacked support from potential allies.
The candidacy of Jorge Macri, who requested a leave of absence from his position as Vicente López mayor in December to become government minister at City Hall, is backed by his cousin, former president Mauricio Macri, and presidential candidate Patricia Bullrich.
Quirós, who serves as City education minister and won plaudits for his handling of the Covid-19 pandemic in the capital, has the support of Rodríguez Larreta.
The City's current mayor praised Acuña's decision, describing it as "enormous."
"The change we need is much more than the sum of its parts. It is a transformation project that already belongs to the people. We did it together in the city and we are going to do it together in the whole country. Being united for what is coming is our responsibility and our obligation," said Rodríguez Larreta, who proposed Acuña as a potential running-mate for the eventual opposition candidate.
Argentina's ruling Frente de Todos coalition has not confirmed who their candidates for the mayoral post will be.
Pollsters expect the opposition to retain control of the capital in this year's elections.