Support for the Greens slumped by a third to 12% in the state of Bremen on Sunday compared with the last election in 2019, according to projected results. The vote reflected a drop in support at a federal level too, to around 15% in opinion polls from a peak of 23-24% last year.

With Russia's invasion of Ukraine and a subsequent energy crisis overshadowing Scholz's first year in office, the Greens won kudos for having long called for a more hawkish stance on authoritarian states and prioritising renewable energy.

The party's relatively youthful leaders were also seen as more outspoken and relatable than Scholz, 64, helping them win new voters.

Their appeal has faded this year, however, as Germans focus more on domestic matters and consider how much the Greens' climate policies will cost and require in lifestyle adjustments. This has sent some voters back to Scholz's Social Democrats or the opposition conservatives.

In Bremen, support for the party dropped after its transport senator Maike Schaefer scrapped the so-called "bread-roll button" on parking ticket machines that gave locals a short spell of free parking to pop into their bakery or other stores.

This was part of a broader Greens campaign to encourage public transport use that has angered many in a country particularly attached to its cars.

Another flashpoint at national level has been a proposed ban on new oil and gas heating systems from 2024, to force the use of green alternatives like heat pumps.

Greens co-chief Ricarda Lang said on Monday the party needed to keep its focus on carbon neutrality but get better at addressing the issue of affordability at the same time.

The party will likely seek to scale back its proposals in future, said political scientist Stefan Marschall at the University of Duesseldorf.

"We're going to see more compromises, less radicalism, which obviously wont suit climate activists," he said.

FADING APPEAL

In Germany's last federal election campaign, the Greens were considered to have a real chance of winning the chancellery, and briefly led opinion polls in mid-2021.

Last year, Greens Foreign Minister Annalena Baerbock, 42, and Economy and Climate Minister Robert Habeck, 53, were the country's most popular politicians.

Approval ratings however in particular for Habeck - the face of Germany's climate and energy policies - have dropped from a peak of 54% to around 30% now, according to pollster Civey.

"Climate protection and sustainability remain important for Germans," said Civey chief Janina Muetze. "But in the last few years of crisis and with growing inflation the willingness to pay for this has shrunk."

Accusations of cronyism within Habeck's economy ministry have also emerged, awkward for a party used to claiming the moral high-ground, analysts said. The Greens deny the accusations.

Greens Environment Minister Steffi Lemke said previous governments had long neglected climate change and this one had to make up for that.

But she acknowledged her party had not found the right tone to address voters and "should have explained more and better".

Sascha Mueller-Kraenner, the national managing director of DUH environmental group, said policies were rushed.

Habeck last year for example had to scrap his proposed gas levy on consumers due to worries about high energy prices and it emerged some energy companies could exploit it. His heating bill has raised technical issues like what to do with buildings unsuited for heat pumps.

"The problem is not that policies are too radical," said Mueller-Kraenner, "but they are not well explained, are often badly done and need improving."