On 4 November 2020, the 240th anniversary of the Rebellion of Túpac Amaru II, Mendoza announced her pre-candidacy with the Together for Peru coalition for the 2021 Peruvian presidential election. Leading up to her candidacy, Mendoza criticized the response to the COVID-19 pandemic in Peru, stating "COVID-19 is showing us many of the country's underlying problems: thousands of families and schools that do not have drinking water, thousands of workers who do not have health insurance, who cannot stop working for a single day because your family's food depends on that, an abandoned public health, of course, we only dedicate 2.3% of GDP to public health, below the average for Latin America which is 4% and well below 6% recommended by the WHO".