Updated 6pm
Switzerland's Green Party was poised to make historic gains in national elections Sunday due to rising fears about climate change, while the anti-immigrant right wing saw its support slip, projections showed.
Ballots were still being counted in the wealthy Alpine nation, but projections released by national broadcaster RTS appeared to confirm the "green wave" that had been forecast before the vote.
The Greens garnered 12.7% of the vote, solidly beating their pre-election projection and marking a five-point bump on their 2015 performance, according the projection by RTS and political research firm Gfs Bern.
Meanwhile, the Green Liberals - an environmentalist party with libertarian socio-economic policies - also gained ground, taking 7.6 percent of the vote compared to less than 5% in 2015.
Surveys before the election showed that climate change had displaced migration as the top concern among the electorate, in what the Sotomo political research institute described as one of the most significant shifts in recent Swiss political history.
The Swiss People's Party (SVP), which has repeatedly been accused of demonising migrants, looked set to remain the largest parliamentary party, with the RTS projecting that it won 26.3% support.
But that is down from the 29% it garnered in 2015.
University of Lausanne political scientist Oscar Mazzoleni told AFP that even a 2% fallback would mark "a failure" for the SVP, and further demonstrate that the party is struggling to attract young voters to replace its ageing electoral base.
The SVP is also the only major party that has not pledged to pursue bolder climate action, having denounced "climate hysteria" in Swiss politics.
'Magic formula'
Speculation will now centre on whether the Greens can force their way into the executive branch for the first time.
Under Switzerland's unique political system, the election decides the 200 lower house lawmakers and 46 senators elected to four-year terms, but the make-up of the executive Federal Council will not be decided until December.
The country's so-called "magic formula" sees the council's seven cabinet positions divided among the four leading parties.
Currently, six cabinet seats are shared equally between the SVP, the Socialist Party and the right-leaning Free Democratic Party, with the centrist Christian Democrats holding the seventh seat.
The presidency rotates each year.
The RTS forecast has the Greens finishing fourth, narrowly beating the Christian Democrats, but it remains unclear if they will emerge strong enough to demand a cabinet slot.
Analysts have said that an alliance of the two main environmentalist parties would be well placed to join the government, but have questioned whether the left-wing Greens and libertarian Green Liberals could agree on a unity candidate.
Overall, the results provided further evidence that a nation where the economy and lifestyle are closely tied to the country's stunning snow-capped peaks has grown increasingly concerned about the ravages of climate change.
A recent study by Zurich's ETH university found that more than 90% of 4,000 glaciers dotted throughout the Alps could disappear by the year 2100 if greenhouse gas emissions are not curbed.