Finland’s former prime minister Alexander Stubb and the country’s former foreign minister Pekka Haavisto have progressed through to the second round of the presidential elections, knocking out a rightwing populist candidate. With all votes counted, Stubb, of the centre-right National Coalition party, had won 27.2% of votes, while the liberal candidate Haavisto, a member of the Green party who is running as an independent, had secured 25.8%, election officials said. Heading into the vote, experts had thought far-right Finns party candidate Jussi Halla-aho might make it to the second round. In the event, he came third with 19% of the vote. Voter turnout was 71.5%. The high-stakes election – the first since Finland joined Nato – to replace two-term president Sauli Niinistö saw a record turnout among advance voters. More than 44.6% of those who were able to vote in advance did so, the equivalent of 1.9 million people. “This is more than I dared to believe,” Stubb, 55, told YLE. “We made it to the second round. That is now clear,” Haavisto, 65, told the crowd at his election party in Helsinki on Sunday night. “I am very happy and satisfied. We have worked hard for this.” A runoff between the two top candidates will be held in two weeks’ time, on 11 February. To be declared president, the winning candidate must receive more than 50% of votes. After a last-minute surge by Halla-aho, liberals had feared there could be two rightwing candidates in the second round. But early results suggested that was unlikely. “I am concerned, but now we have to follow the will of the voters,” Haavisto, who would be Finland’s first out gay and Green president, told the Observer on Friday at a campaign event. Taking place against a backdrop of escalating geopolitical drama on the border with Russia, Finland’s first election since joining Nato is seen as the most high-stakes in living memory. The president – who is head of state and commander-in-chief of the army and is responsible for foreign policy, in cooperation with the government – represents Finland at Nato summits and in meetings with international leaders, so is seen as crucial to the country’s direction. Stubb, who was prime minister from 2014 to 2015 and has spent eight years in government, told the Guardian on Friday that he came out of political retirement because of Vladimir Putin’s invasion of Ukraine. He said: “Having been in government for eight consecutive years and having held all the key portfolios, I felt in 2016 that I had very much done it for God and country, as they say. My plan was not to return to politics, or certainly not to national politics … but Putin’s attack on Ukraine changed it.” In the current climate, he said, foreign and security policy was “existential” for Finland, which has closed its entire land border with Russia. After Finland joined Nato in record speed last April, he said the country was entering “a new age in Finnish foreign policy”. He said: “When it became evident, right at the beginning of the war, that our path towards the alliance would begin, I felt strongly that this was a new age in Finnish foreign policy and perhaps I could throw my hat into the ring once again.” The election so far has centred largely on international and security issues, including Russia, Ukraine, Gaza, the US elections and Nato membership. But in the past few weeks, debates between the nine candidates had focused more on domestic issues, benefiting the Finns party candidate.