

At the critical moment Koivisto managed to gain the support of the SKDL. In the spring of 1981, members of Centre, which was serving as part of the government coalition, launched a behind-the-scenes attempt to bring down the government through a parliamentary motion of no confidence, so that Koivisto would not be able to conduct a presidential election campaign from the position of Prime Minister. In early 1981, President Kekkonen began to regret Koivisto's appointment as Prime Minister and started to offer support to those who wanted to get rid of him. As Prime Minister and chairman of the Bank of Finland who enjoyed high ratings in opinion polls, Koivisto began to be seen as a likely future candidate for the presidency. By this point there was increasing dissatisfaction with the aging President Kekkonen, whose failing health was becoming difficult to conceal, and also a perceived lack of change.

The 1979 election saw him return as Prime Minister, forming a coalition government between the SDP, Centre, SPP, and SKDL. For most of the decade, Koivisto concentrated on his work as the chairman of the Bank of Finland. To counter this, he threw his weight behind Koivisto's Social Democratic colleague, Kalevi Sorsa. In the 1970s, President Kekkonen started to regard Koivisto as a potential rival. He served as Prime Minister for two years until the 1970 parliamentary election, which saw the other parties in the coalition government – Centre, SKDL, SPP, and TPSL – suffer heavy losses, bringing about Koivisto's resignation.

Koivisto became the Prime Minister of his first government, the Koivisto I Cabinet, on 22 March 1968. By the beginning of 1968, many SDP members had become disillusioned with Paasio's leadership style, and Koivisto emerged as the chief candidate to succeed Paasio as Prime Minister. The 1966 parliamentary election's Social Democratic victory saw the formation of a government under Prime Minister Rafael Paasio, with Koivisto, the party's expert on economic policy, assuming the role of the Minister of Finance. Minister of Finance Koivisto reads the 1967 draft revenue and expenditure estimate. The Communist newspapers branded Koivisto as their number one enemy due to his status as a major figure in the struggle for control of the trade unions. Koivisto went to Hanko to take charge of the harbour-master's office and recruit workers to break the strike, the government having banned strike action. In 1949 communist-controlled trade unions attempted to topple Karl-August Fagerholm's social democratic minority government, and the Social Democratic leadership of the Finnish Confederation of Trade Unions (SAK) declared the port of Hanko an "open site", urging port workers who supported legality to go there. In December 1948, he was appointed the manager of the Harbour Labour Office of Turku, a post he held until 1951.

In 1948 he found work at the port of Turku. During his early years, Koivisto was also influenced by anarchism and anarchosyndicalism. Īfter the war, he earned a living as a carpenter and became active in politics, joining the Social Democratic Party. While reflecting on his wartime experiences later in life, he said "When you have taken part in a game in which your own life is at stake, all other games are small after that". During the war he received the Order of the Cross of Liberty (2nd class) and was promoted to the rank of corporal. This detachment was only open to selected volunteers. During the Continuation War, Koivisto served in the Infantry Detachment Törni led by Lauri Törni, which was a reconnaissance detachment operating behind enemy lines. After attending primary school, Koivisto worked a number of jobs, and at the beginning of the Winter War in 1939 joined a field firefighting unit at the age of 16. Koivisto was born in Turku as the second son of Juho Koivisto, a carpenter at Crichton-Vulcan shipyard, and Hymni Sofia Eskola, who died when he was 10. Young Mauno Koivisto was one of soldiers led by legendary Lauri Törni during the Continuation War.
