Q&A: German parliamentary election

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Media captionStephen Evans explains how the Bundestag election works

On 22 September, German voters will go to the polls to elect a new Bundestag, the country's lower house of parliament.

Chancellor Angela Merkel's centre-right Christian Democrats and their allies are defending a majority of 40 in the current 620-seat assembly.

Who are the key players?

The Christian Democratic Union (CDU), its Bavarian sister party (CSU) and the pro-business Free Democratic Party (FDP) have pledged to renew their governing coalition with Angela Merkel as chancellor if they win another majority.

Image caption Mr Steinbrueck and the SPD have focused on social justice

The Social Democratic Party of Germany (SPD) is the biggest opposition force. Its candidate for the post of chancellor, Profile: Peer Steinbrueck, was finance minister in Mrs Merkel's grand coalition between 2002 and 2005. The SPD's declared aim is to govern with the Greens as a junior coalition partner.

Three other parties currently hold seats in the Bundestag. The Left Party, which is particularly popular in the former East Germany, is the fourth-biggest force, behind the FDP and ahead of the Greens.

Contenders not represented in the current parliament include the Pirate Party and the new anti-euro Alternative for Germany (AfD).

What are the main issues?

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Media captionGerman voters on the issues that matter most to them ahead of 22 September's elections.

The governing parties have emphasised their record in managing the economy and steering the country through the eurozone crisis. "We have shown that we can do it, and this in difficult times," Mrs Merkel said during the campaign's only televised debate between her and Mr Steinbrueck.

The SPD has focused on social justice and advocates a national minimum wage. "We want to be fairer and at the same time hold this society together," Mr Steinbrueck said during the TV duel.

The FDP wants a reduction in state debt, while the Greens are calling for "clean and affordable forms of energy for all".

The Left Party has campaigned on labour market reform and pension rights. It argues that the SPD's plans for social justice lack credibility.

Polls suggest that top issues for voters include the eurozone crisis, unemployment and social policy.

How does the system work?

Image caption Recent polls credit the CDU/CSU with about 40% of the vote

The German electoral system is based on proportional representation.

Each voter has two votes - the first for a candidate in their constituency and the second for a political party.

299 seats are allocated to constituency candidates, who need to win a simple majority locally to take a seat in parliament.

A further 299 seats are allocated to parties so that the total distribution reflects how second votes were cast nationwide, but only if the party obtains at least 5% of second votes or wins in at least three constituencies.

Candidates who win in their constituency are guaranteed a seat regardless of their party's share of second votes. This usually leads to the total number of seats being higher than the nominal 598.

Under this system, no party has achieved an absolute majority since 1957 and coalition governments have been the norm.

Which outcomes are most likely?

Recent polls credit the CDU/CSU with about 40% of the vote, way ahead of the SPD on about 25%. However, with the FDP hovering around the 5% mark, it is not clear whether the party will even be available to form another coalition under Angela Merkel.

Another possibility is a grand coalition bringing together the CDU/CSU and the SPD, although Mr Steinbrueck has ruled out his participation in such a deal.

The SPD's favoured outcome of a coalition with the Greens looks like a remote prospect as most polls put the two parties together at little more than 35%.

Other constellations, such as a CDU/CSU/Greens or SPD/Greens/Left coalition, have been debated in the media but are seen as unlikely.

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