Duhalde began his political career in Zamora, his hometown and a Buenos Aires suburb. He served first on the City Council (1973) and then as mayor (1983). In 1987, he won election to represent his home district in the National Congress; during his term, he was elected vice president of the Chamber of Deputies. Duhalde was then hand-picked in 1989 to run for vice president on the ticket with Carlos
Menem, but after two years in the Menem administration, relations between the two powerful men deteriorated and Duhalde left to run for governor of the province of Buenos Aires. He was successful and took over the leadership of the province, where about one-third of Argentina's population lives. He was reelected in 1995. In 1999, he ran unsuccessfully for president against Fernando de la Rúa, who took office in December 1999 promising to focus on the economy. In 2001 Duhalde was elected to represent the province of Buenos Aires in the national Senate.
In late 2001, with the economy in chaos, de la Rúa resigned. After three other candidates each briefly moved into and out of the president's office in the days immediately following de la Rúa's December 2001 resignation, Eduardo Duhalde was approved by National Congress (dominated by the Partido Justicialista—Justicialist Party) to assume the presidency in early January 2002. Because Duhalde had not been elected by the people, he faced an even greater challenge in winning popular support for the painful economic reforms necessary to bring the Argentine economy out of its nosedive.