Die Linke has hit a rich seam of support by calling for withdrawal from Afghanistan
By Steve Rosenberg
BBC News, Goettingen
On a market square in western Germany, in front of 100 people, a German MP sings about life being just like a game of Monopoly.
The Bundestag bard is Diether Dehm, from Die Linke - the Left party. The monopoly game in his song is an ideological tussle between capitalism and the workforce. Mr Dehm tells me that his party is the only one in Germany to really care about the workers.
"I look at other parties and I see that their chiefs and representatives look like talking robots, without skin and without a heart," he tells me.
"And I think that the working movement is something that always comes from the left side of the body. And this is the heart."
The Left party is certainly taking heart from the opinion polls. The party, which combines disaffected Social Democrats from western Germany with former East German communists, is tipped to get more than 10% of the vote in Sunday's parliamentary election.
When Mr Dehm puts his guitar down, on comes visiting candidate Sarah Wagenknecht to talk policy. In a fiery speech she denounces capitalism and privatisation; she calls for more state ownership and for a minimum wage for workers. The crowd applauds.
MP Diether Dehm is trying to rally those who feel let down by society
While Germany's larger parties have kept their election promises frustratingly vague - with slogans like "Confidence" (the Christian Democrat CDU) and "Our Country Can Do More" (the Social Democrat SPD), by contrast the Left has been far more specific.
"German Troops out of Afghanistan," says one poster on the square; "Tax Wealth," says another. "No to Nuclear Power," another. And there are leaflets entitled: "More money for Education, Less for the Banks."
"I think it's a very successful campaign to use these concrete slogans," says political commentator Michael Weidemann. "Many people who are not close to the Leftists might vote for them. Because they are the only party which acts this way."
The Left's slogans certainly strike a chord with Wolfgang Echterhoff. On the outskirts of Bochum, he shows me the giant Nokia factory where he used to work. When the plant was relocated to Romania, Wolfgang was among 1,500 German workers who lost their jobs.
"Lots of my old work colleagues and my drinking mates are now supporting the Left party," Mr Echterhoff says.
"People are frightened that in Germany the gap between the rich and the poor is growing wider."
If the Left party now claims the political left, where does that leave Germany's centre-left Social Democrats? The SPD has always claimed that it is the voice of the workers and the party of social justice.
But that has become an increasingly hard sell. When the previous SPD Chancellor Gerhard Schroeder pushed through painful welfare reforms which slashed state benefits, many SPD members left the party in disgust. Some went over to Die Linke.
Since then, four years of grand coalition government - with the Social Democrats as junior partner - have weakened the SPD even further.
"It's especially bad for the SPD," believes Michael Weidemann. "They have already lost a lot of the voters to the Green Party in the 1970s and 1980s. And now there are a lot of traditional SPD voters who are vanishing. The SPD may not be big enough in the future to even lead a two-party coalition."
No willing partner
At a Left party information stand in the centre of Bochum, former SPD supporter Brunhilde Michaelis hands out leaflets, posters and balloons to passers-by. She believes the Left party has become what the SPD used to be, and what it should be.
The SPD's Frank-Walter Steinmeier has found his support eroded by the Left
"What does the SPD do for us people on the street? Nothing," Ms Michaelis complains.
"They work together with the CDU [the main governing party]. And the CDU has always been the party of the capitalists. The SPD loses its image. I think it's more the Left party - us - who are the real socialists."
Back at the Left party rally, musical MP Diether Dehm is performing one final song.
"Even if we are small and weak," he sings, "just like water, we can rip down the thickest walls." It's a rallying cry to those Germans who feel abandoned by society.
Mr Dehm's party will not win this weekend's German election. It is not about to enter national government, because none of the other main parties are prepared to share power with it.
But if it does well in the polls, that will increase the pressure on Germany's Social Democrats. The SPD may be forced to consider a future alliance with the Left, if it wants to be in power.