Swiss voters have shifted the country’s political direction decisively leftward in elections that delivered a triumph for two environmentally focused parties and reversed decades of gains for the country’s hard right. The Swiss Green party increased its share of the nationwide vote by 6 percentage points in Sunday’s polls, giving it 13.2 per cent overall. The Green-Liberal party meanwhile took 7.8 per cent, up 3.2 percentage points from the last federal election in 2015.

The swing – though modest in comparison to recent political ructions elsewhere in Europe –  represents the largest parliamentary shift in the alpine state’s ordinarily finely balanced political system.The Greens will gain 17 seats in the 246-seat federal assembly, doubling their existing tally and eclipsing the hard-right Swiss People’s party’s previous record-breaking 15-seat gain in 1999. The Green-Liberals will gain a further nine seats. Together the green bloc will hold at least 44 seats, making it the second-largest in the parliament.

Regula Rytz, the Greens’ party leader, said on Sunday evening that they would bid for one of the seven seats in Switzerland’s government, known as the federal council. That could fracture the existing consensus in Swiss politics and pave the way for an intense period of political dealmaking in the months ahead.

The seven seats in the council are traditionally allocated to the four largest parties in the National Assembly in a convention known as the “magic formula”. Recent years have seen the arrangement favour the parties of the right.