Angela Merkel's necklace, a middle-finger photo and "Veggie Day" have been hot-button issues in a general election campaign that Germans say has been shockingly banal.

With Sunday's election shaping up to be nail-bitingly close, Merkel and her election rival Peer Steinbrueck have pulled out all the stops at the stump in the final days to mobilise supporters.

But persuading Germany's 62 million voters to turn out might prove un uphill struggle, given that two thirds said the campaign has disappointed in a Forsa poll published Wednesday.

"Is Merkel too boring for Germany?", "The Hullabaloo Republic" and "Deceptive Boredom" -- Germany's headline writers have not pulled any punches in their criticism of how the campaign has been handled.

Despite several TV appearances by conservative Merkel and Steinbrueck of the Social Democrats (SPD), nearly half of respondents grumbled in the poll for Stern news weekly that the parties had failed to address issues close to their heart.

Standing in front of Berlin's iconic Brandenburg Gate, Marian Gruemmele, 20, from southwestern Baden-Wuerttemberg state, told AFP he was unhappy about Merkel's failure to push for a minimum wage.

"I believe that at the moment quite a lot is going wrong especially with the minimum wage. On that I'm already very disappointed, therefore I'll vote for the SPD," he said.

The Syria crisis, howls of protest over mass US online spying, wages, pensions and childcare issues have struggled for prominence in a personality-driven campaign where the favourite is running on her track record.

Meanwhile, a highly anticipated TV debate between the top two contenders prompted fervent online chatter about Merkel's necklace sporting the colours of the German flag and immediately gained its own Twitter account.

And Steinbrueck's surly middle-finger pose on the cover of a news magazine unleashed heated debate in the last pre-vote week which the self-styled straight-talker sought to quell, arguing the need for campaign "humour".

Political magazine Cicero criticised the "political junk food" that resulted, it said, from most Germans having inwardly long turned away from politics amid an ever-more complex landscape and Brussels' growing power.

"But it doesn't replace debate," it warned, also blaming Merkel for adding to the "lethargy".

Steinbrueck has struggled to score political points after seeing traditional centre-left issues such as a nuclear exit snatched away by Merkel and accuses her of lulling voters into a false sense of security and using empty political phrases.

Merkel's trump card is the economy, with a giant poster on Berlin's main train station of just her now famous diamond hand gesture suggesting Germany is in good hands for another four years.

And a call by the opposition Greens for a weekly "Veggie Day" in work canteens has faced ridicule.

Political scientist Gero Neugebauer, of Berlin's Free University, blamed voter disappointment on a lack of discussion on important subjects because neither side wanted to debate them, leaving voters confused.

"The (campaign) posters are boring, they block the view of the driver and when you pass by you can't read anything anyway... the slogans are so stupid that you don't generally know at all what is actually meant by it," he told AFP.

Merkel holds a steady lead but under Germany's system of coalition building every vote counts, especially amid what Spiegel news weekly termed a non-voter movement that has become "socially acceptable".

Latest polls show Merkel's current centre-right coalition with the ailing Free Democrats in a tug-of-war for votes with disparate opposition parties.

"We will fight for every vote," Merkel vowed this week.

Former Social Democrat chancellor Helmut Schmidt told Wednesday's Bild daily if Germany's traditionally high voter participation dropped this time around it would be down to Merkel's election campaign tactics.

"If it were to sink this time actually to below 70 percent, then certainly also because Mrs Merkel is telling people they shouldn't be concerned," he said, pointing in particular to Europe's financial crisis.