He has been several times a minister for Democrazia Cristiana (DC); notably during his stay at Viminale (Ministry for internal affairs) he re-structured Italian police, civil protection and secret services organisations. He was in charge during the kidnapping and murdering of Aldo Moro by Red Brigades and resigned when Moro was found dead in 1978.
Resigning from his post, he earned the respect of the opposition (in particular of the Italian Communist Party) because he appeared as the only member of the government who took responsibility for the tragic conclusion of the events. This led to his election in 1985 as President of the Republic (Head of State), in which for the first time ever a candidate won at the first ballot (where a majority of over ⅔ is necessary, which would subsequently decrease in later ballots). The only other president of the Italian Republic elected at the first ballot was Carlo Azeglio Ciampi in 1999.
However, in his last two years as a President, Cossiga began to express opinions, at times virulent, against the Italian political system. In his opinion, Italian parties, and especially DC and PCI, had to take into account the deep change that the fall of the Berlin Wall and the end of the Cold War would have brought.
These declarations, soon dubbed "esternazioni", or "mattock blows" (picconate), were considered by many inappropriate for a President. Cossiga declared he was just "taking pleasure in removing some sand from my shoes". Cossiga was supported by the secretary of the Italian Socialist Party, Bettino Craxi.
A strong tension with the President of the Council of Ministers Giulio Andreotti emerged when Andreotti revealed the existence of Gladio, a Stay-behind organization with the official aim of countering a possible Soviet invasion through sabotage and guerrilla warfare behind enemy lines. Cossiga declared his involvement in the setup of the organization. The Communist Party started a procedure for impeachment (Presidents of Italy can be impeached only for high treason against the State or Attempt against the Constitution). The request of impeachment was subsequently withdrawn.
Cossiga resigned two months before the end of his term, on April 28 1992. He was voted again for president by the Italian Social Movement, which had supported him in his campaigns.
In February 1998 Cossiga created the UDR party (Unione Democratica per la Repubblica), declarately a centrist political formation. The UDR was a crucial component of the majority that supported the D'Alema government in October 1998, after the fall of the Prodi government which lost a confidence vote.
Cossiga declared that his support for D'Alema was meant to end the conventional exclusion of the former Communist Party (PCI) leaders from the premiership in Italy.
He remains a vocal commentator of Italian politics.