In 1977, he was elected president of Athletic Bilbao in the early days of the Spanish transition to democracy; under his mandate the club began to officially display the Basque flag.
[1] Other changes during his tenure included naming Javier Clemente as manager, putting the presidency up for universal suffrage of club members and allowing women to become club members.After turning down a plan by his predecessor to build a new stadium, instead renovating for the 1982 FIFA World Cup, Duñabeitia left Athletic Bilbao in 1982 and became a full-time politician.
[2][3] In 1983, he was elected to Bilbao City Council and became the councillor in charge of social welfare, under mayor José Luis Robles.
After the resignation of José María Gorordo, he became mayor in December 1990, serving until the June 1991 election.
[1] His funeral at Bilbao Cathedral was attended by colleagues from local football and politics.