Surging Greens shake up German coalition politics
The talk in Darmstadt is of the "green wave".
One in three voters in this city near Frankfurt backed the Greens in the Hesse state election last month.
In the city centre, workmen are setting up a Christmas market in freezing drizzle.
There were workmen here just over three years ago too. Then, they were preparing for a street party: Darmstadt had turned out to welcome its refugees.
Since then, migration policy has redefined German politics. Angela Merkel's centrist coalition government has bickered, dithered and shifted to the right.
As a result, voters have walked away from her Christian Democrats (CDU) and the centre-left Social Democrats (SPD).
Many have chosen instead the far-right Alternative for Germany (AfD), but also more recently the resurgent, and far more liberal, Green party.
Why the Green surge?
The Greens' strong performance has taken many by surprise. First they scored well in the Bavarian election last month, then here in the state of Hesse. And, were Germany to hold an election tomorrow, polls suggest the party would come second, just a few points behind Mrs Merkel's conservatives.
Singers arrive at a warm, brightly lit church hall near the city centre, faces flushed with cold, pulling off hats, gloves and scarves.
"We have a lot of students, a lot of young people, but also a mixture of cultures and people, from engineers to people who work with kids, or in the zoo," said Alison. "I think that's one of the reasons the [Green] party is so big here."
"They're riding on a wave right now," said Gudrun. "Especially with AfD coming up, people are starting to think, 'OK, where can I make a point'? And that's what brings them to the Greens."
"But on the other side we've got climate change," she says. "A lot of people really believe that it could happen and it's really affecting us. Especially this summer it was so extreme and I think that's one of the reasons why."
But the Greens will need more than environmental policy if they are to cement their status as Germany's second-strongest party.
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Are they trusted?
Steffen Ross runs a bicycle shop near the city centre.
"Business and the Greens are an uneasy couple. The Greens want growth, but they don't want a lot of things that are associated with growth," he says.
He cites the Greens' promise to shut down "dirty" coal-fired power stations, and their wariness about fully embracing new digital technology, in case it infringes citizens' privacy.
As we talk, a couple of well-wrapped cyclists speed past the door, on a brand-new cycle lane courtesy of the local Greens. Steffen agrees the party has been good for his business. "But for me the question is: can the Green party operate effectively in questions of economics and politics?" he adds.
On that point, the party is trying hard. It has revamped its image and its new leaders - Annalena Baerbock and Robert Habeck - are determined to play down the party's left-wing protest past.
Who are the Greens?
The Greens have their roots in the environmental and peace movements of the 1970s.
Long defined by their opposition to military intervention and nuclear energy, and their calls for a more ecologically minded Germany, they first took seats in the Bundestag in 1983 and joined two coalition governments - both with the SPD.
Their appeal to voters was for many years somewhat diminished by infighting between the radical left (so-called "Fundis", or fundamentalists) and the more pragmatic or centrist "Realos", or realistics.
It's less of an issue for the party now. These days the Greens have their sights on the centre ground.
What's interesting about Hesse is that the Greens and CDU are negotiating to renew a regional coalition government here. Analysts predict that it could be a model for Germany's next governing alliance at federal level. But they would have to overcome significant differences - not least on migration.
"We don't even have common ground to talk about migration, because we haven't managed to pass an immigration law yet," says Hildegard Förster-Heldmann, a Darmstadt Green politician elected with more than 30% of the vote. "That would be the first step. Then we can step-by-step convince people and create common ground."
She faces the same challenge as her national colleagues: how to keep the momentum going.
"The subjects we work on - the environment, resources, sustainability, are subjects which affect everyone," she says.
"The Greens were the only ones who managed to show those subjects were interconnected. If we keep working on that, we might be able to keep the voters who supported us on impulse."
Some see the success of the Greens as an antidote to the far right. But Dirk Jörke, a professor of political science at Darmstadt University, is wary.
"I don't believe this will make right-wing populism disappear - quite the opposite. It will lead to an increasing division and the debate will become more morally charged. In the end that will not contribute to the decline of far-right populists, but rather confirm them."