Early returns in Finland’s parliamentary election on Sunday have the centre-left Social Democratic Party in first place, with most of the ballots that were cast in advance already counted.

Initial results from the pool of 1.5 million advance votes, representing 36% of eligible voters, were published minutes after polls closed in what appears to be a tight race.

The Social Democratic Party had 18.9% percent of advance votes from the uncompleted tally and the National Coalition Party 17.2%.

Outgoing Prime Minister Juha Sipila’s Centre Party and the populist Finns Party were close with 15.4% and 15.1% respectively.

In an election that was dominated by debates about climate change, the Greens had 11.4%.

Officials said some 300,000 advance votes remained uncounted when polls closed on Sunday afternoon.

Petteri Orpo, chairman of National Coalition Party (Jussi Nukari/Lehtikuva via AP)

The election followed a campaign in which concerns about climate change even overshadowed the issue of how to reform the nation’s generous welfare model.

Finland, a European Union member of 5.5 million people, has one-third of its territory above the Arctic Circle. Most political parties support government actions to curb global warming.

“For everybody, it’s about the climate. It’s kind of a climate election. Everybody’s feeling some kind of a depression about it,” voter Sofia Frantsi, 27, an interior architect from Helsinki, told The Associated Press on Sunday.

Voters chose between 2,500 candidates from 19 political parties and movements for the Eduskunta legislature’s 200 seats. More results were expected later Sunday night.

“It’s clear a vast majority of Finns are hoping that the new parliament takes climate action,” Emma Kari, a Greens lawmaker, told the AP as she campaigned on Saturday. “Politicians need to take responsibility.”

Greenpeace Finland called Sunday’s vote the “climate election,” saying that “never before has climate and the limits of planet Earth been discussed with such seriousness in Finland”.

The environmental group cited a recent nationwide poll in which 70% of respondents said tackling climate change and reducing carbon footprints should be key priorities for the new government.

Finland is boosting its production of nuclear energy by launching a new nuclear power plant next year. Finnish lawmakers last month voted to phase out burning coal as an energy source to end it by 2029.