The far-left Left Party's victory in the Berlin state election on Sunday was overshadowed by the continuing advance of the far-right in eastern Germany but it marked another defeat for Chancellor Friedrich Merz's ruling coalition.

Lead candidate Elif Eralp campaigned on the soaring cost of housing in the German capital and immediately promised to follow through with a pledge to nationalize private housing associations that account for a large share of the city's housing stock.

The result, which roughly doubled the party's previous score, could see her become the first mayor of Berlin from the Left Party, which grew out of the former East German communist party, following the reunification of the country 36 years ago.

With counting still going on late on Sunday, ⁠it was already clear that her party were set to displace Merz's conservative Christian Democrats (CDU) from the mayor's office.

"From today, we're changing Berlin together," she told celebrating party members in Berlin.

The Left Party took 25.3%, ahead of the CDU on 19% and the far-right Alternative for Germany (AfD) on 16%. It also far outstripped the centre-left Social Democrats (SPD) on 12.1%.

In her first remarks after the polls closed, the 45-year-old daughter of left-wing Turkish parents who fled a coup in 1980 said the increasingly difficult rental situation was "the biggest social problem" in the capital.

She promised to proceed with nationalising the housing associations and "drive speculation from Berlin," in accordance with a referendum from 2021 in which 58% backed proposals to legislate for nationalisation.

Whether the policy, which would see some 220,000 housing units transferred to state ownership, is ever adopted remains ⁠unclear. SPD general secretary Tim Kluessendorf said nationalising the housing associations would cost some €20 billion.

An Infratest Dimap poll also found only 37% of those surveyed were in favour.

Sunday's election in Berlin came on the same day the AfD followed up on its success in the September 6 Saxony-Anhalt election by taking first place in an election in Mecklenburg-Western Pomerania state. It also recorded its best-ever result in Berlin.

But while the AfD has attracted most attention, the ⁠Left Party has also benefited from a general turn against the mainstream parties of the centre-left and centre-right.

As in the four other state elections held this year, the dire state of the German economy and uncertainty about the way ahead weighed on the election in Berlin, with the main focus ⁠fixed on rental costs.

But significant obstacles remain for Eralp.

Both the SPD and the environmental Greens signalled a willingness to join a coalition with the Left Party. But the Greens leader Felix Banaszak said accusations of antisemitism that have been levelled against parts of the Left ⁠Party in Berlin had to be addressed for a partnership to work.

"We need a clear commitment to combating antisemitism; otherwise, things won't work with us," he said.

The Left Party rejects accusations of systematic antisemitism, saying it is against all forms of "group-focused hostility" including antisemitism, racism and sexism. It did not immediately respond to a request for comment on Banaszak's demand.