German voters will head to the polls in a pivotal election a month from today.

       But many appear to be undecided ahead of the September 26 vote.

       After 16 years of Angela Merkel as chancellor, polls show that 25 per cent of the population can't decide between Annalena Baerbock of the Greens, Armin Laschet of the centre-right CDU or Olaf Scholz of the centre-left SPD.

       In the latest survey by the polling institute Forsa, the SPD has just pulled ahead of the CDU/CSU (Union) with 23 per cent.

       A month ago, the CDU/CSU was up to 30 per cent, far outstripping the SPD. Now the poll puts the Greens at 18 per cent and the FDP (Liberals) at 12.

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       According to Gregor Zons, a senior researcher at the Düsseldorf Party Research Institute (PRuF), the reason behind the indecisiveness is the fact that the candidates have not previously served as prime minister.

       "First of all, this is a special election campaign, because for the first time in Germany we have the situation that an incumbent chancellor is not running for re-election. That means it's clear that we will have a new person in the office."

       A coalition government is also a possibility, but there too, Germans are still undecided.

       Angela Merkel announced in 2018 that she wouldn't seek a fifth four-year term.