By Steve Rosenberg
BBC News, Berlin
Germany's political landscape is so fragmented, no single party can get enough votes to form a government by itself.
So once all the votes are cast and counted, the parties in parliament will need to do deals, agree alliances, try to form a working coalition. And that makes a German election a surprisingly colourful affair.
For the last four years, Germany has had a black-red coalition in power - black, the colour of the centre-right Christian Democrats, led by Chancellor Angela Merkel, and red their traditional rivals the centre left Social Democrats.
But in this election Germany's two largest parties are seeking new partners.
Mrs Merkel wants her Christian Democrats to share power with the pro-business Free Democrats, creating a black-yellow coalition that would push ahead with tax cuts and welfare reforms.
Also possible, though less likely, is the Christian Democrats teaming up with both the Free Democrats and the Green Party - creating a so-called Jamaica coalition of black, yellow and green.
And what about the reds - the Social Democrats? Well, their candidate, Frank-Walter Steinmeier, the current foreign minister, is dreaming of a red-green government, in a tie-up with the Green Party. That is the combination that led Germany under Chancellor Gerhard Schroeder between 1998 and 2005. But opinion polls suggest that neither red nor green will get enough support to make that possible this time.
They could try to persuade the Free Democrats to join them, in a red-yellow-green government, a so-called traffic-light coalition. But the Free Democrats claim they are not interested.
One alliance the Social Democrats themselves have ruled out is teaming up with the far-left anti-capitalist Die Linke, or Left party.
Which means perhaps the only way the SPD can stay in power is - once again - as junior partner in another black-red grand coalition. With Angela Merkel remaining chancellor.