A member of the Social Democratic Party (SP/PS), he was President of the Swiss Confederation in 2001 and 2006.

Leuenberger was elected to the Federal Council on 27 September 1995 as a member of the Social Democratic Party, succeeding Otto Stich.

Leuenberger was presented with the Political Award for his work to build and maintain a sustainable transportation policy.

[5] This led to the situation that the parliament would have had to elect a new Federal Councillor both in September and November.

To avoid this situation, Leuenberger then announced he would change his resignation to allow for just one election for both new Federal Councillors.