"There's always reason for hope," said Social Democrats (SPD) voter Monika Hermann. And she isn't alone in her optimism.

At an SPD rally in Potsdam, Brandenburg on Friday, turnout was high, with several hundred supporters waving their red paraphernalia and EU flags on the city's Luisenplatz. But with the Social Democrats polling at 20 percent in the latest DeutschlandTrend poll, it seems the party will need more than hope if they have any chance of closing the 17-point gap between them and Chancellor Angela Merkel's Christian Democrats (CDU).

Read more: German election: SPD sinks to 20 percent in latest poll

Ardent SPD member Lena Cociani, 23, said, however, that the latest polls should be taken with a pinch of salt.

"Look how inaccurate the polls were before the US election and the Brexit," she said. "We can't bank on these polls reflecting the result on September 24."

Read more: Who is Martin Schulz, the SPD challenger to Angela Merkel?

Accurate or not, the polls signal a huge shift in voter preference since earlier this year. Shortly after the SPD announced Martin Schulz as its chancellor candidate the party saw a spike in popularity that was attributed to what, at the time, was being dubbed the "Schulz Train," attaining more 30 percent in the polls.

Canine support

And yet, seven months later, the SPD's support seems unable to stop sinking. Speaking volumes of Germany's election campaign, excitement at Friday's rally peaked when a terrier, sporting a red hoodie, decided to steal the limelight. But as Schulz reached out to stroke it, even the dog ran away.

"Oh no," he said. "I was just about to give him a ballot paper."

For the dog it was most likely the offer of a biscuit in the second row, but what is it that's driving the voters away?

Pensioners Mr. and Mrs. Wiegank, who spent most of their lives in former East Germany, said the SPD would have benefited from not voicing their support for a coalition with the Left Party and the Greens.

Read more: A guide to possible coalitions for Berlin's new government

The fact that some of the Left's members were once part of the SED, which ran the East German dictatorship, remains a gripe for many voters.

After the fall of the Berlin Wall, the SED evolved into the Party of Democratic Socialism (PDS) and throughout the 1990s established itself as a quasi-communist opposition faction.

But Mrs. Wiegank will still be voting for the SPD on September 24, with one reason always drawing her back. "The fact that the SPD were the only party to vote against Hitler's 'Enabling Act' [which paved the way to his dictatorship] still strikes a note with me," she said.

Need for change

Even if the optimism among voters is realized on September 24,  voters at the Potsdam rally were unanimous on one thing: the SPD needs a new concept.

Like Konak, first-time voter Lena Zoc Volkmann said the SPD has suffered as a result of being a junior partner in the so-called Grand Coalition with the CDU.

"They’ve lost their own policies and what they stand for," the 18-year-old said.

The founding of the SPD dates back to 1863 in the shape of the General German Workers' Association (ADAV). For decades they remained the "workers party," for the "every man," the blue collar workers, the "little man" as the Germans say.

Read more: The SPD - Germany's oldest political party

But Germany's working landscape has changed," said Volkmann. "Today the SPD has the chance to reach out to young voters. Especially those who support a stronger European Union."

Social equality, which for years has been the SPD's leading campaign issue, has also fallen off the radar during this election, Volkmann said. "A lot of people think Germany's prospering. So instead, voters seem to be more concerned with domestic security and migration."

Orhan Konak has already cast his ballot by postal vote - but didn't divulge his party of choice. He believes that being the main opposition in the German parliament would be advantageous not only to the SPD, but would also offer disillusioned voters a "real alternative," as a opposed to the far-right Alternative for Germany (AfD).

Read more: Martin Schulz calls AfD incompatible with German constitution

"The SPD aren't going to be the major partner in a coalition. So they'd be better off being the main opposition. Then they can redefine themselves," he said.

At the rally on Friday, a llive band welcomed voters with a rendition of Daft Punk's "Get Lucky." And despite the optimistic voters, it looks like the SPD could be counting on doing just that in the coming week. But whether or not the result correlates with the polls come September 24, the SPD has its work cut out - not only in the next nine days, but also in the next four years of parliament.