Flavio Bolsonaro, the Brazilian senator defeated in Sunday's presidential election, was expected to arrive in Miami on Wednesday after leaving Brazil despite a Supreme Court order requiring him to surrender his passports.
His departure, following a journey through Argentina and Ecuador, comes as US President Donald Trump's administration prepares to grant entry visas to Bolsonaro and his family.
Argentina's migration authorities confirmed that Bolsonaro crossed the Tancredo Neves International Bridge late Tuesday with his wife and two daughters, ending more than 24 hours of uncertainty about his whereabouts.
The family subsequently boarded a private aircraft operated by Baires Fly at Puerto Iguazu airport, departing shortly after midnight for Guayaquil, Ecuador.
Flight-tracking records showed the aircraft landing in Guayaquil at 3:46 a.m. before continuing toward Miami's Opa-locka Executive Airport, with arrival scheduled for 9:18 a.m. local time.
Authorities have not clarified how Bolsonaro entered Ecuador or how he reached Argentina after disappearing from public view on Monday.
Brazilian federal police have faced criticism for failing to prevent his departure despite concerns that he might flee following his unexpected election defeat.
Trump confirmed his willingness to receive Bolsonaro after a senior State Department official indicated that the senator and his family would receive US visas.
Brazilian President Luiz Inacio Lula da Silva condemned the departure, while accusing Washington of supporting efforts to restore the Bolsonaro family's political influence.
The developments threaten to deepen an existing diplomatic dispute between Brazil and the United States.
Bolsonaro had been considered the favorite before losing Sunday's election to Lula, intensifying scrutiny of his subsequent movements.
His father, former President Jair Bolsonaro, previously travelled to the United States after his 2022 election defeat and was later sentenced to 27 years in prison for plotting a coup.
Flavio Bolsonaro faces potential legal exposure when his Senate immunity expires in February.
On Monday, he publicly denied intending to leave Brazil and pledged to comply with the court's passport order.
His departure has renewed questions about judicial enforcement and the growing diplomatic consequences of Brazil's disputed political transition.