Despite a likely victory, Merkel faces some tough coalition choices
Barring an upset, Angela Merkel will continue to lead Germany after this weekend's vote, but in combination with one or more of her rivals.
Although a surprise cannot be ruled out, pollsters are confident Mrs Merkel's conservative CDU will win the most seats in the Bundestag lower house.
All parties have ruled out joining the right-wing Alternative for Deutschland in a coalition, but most other combinations are on the table. Based on the numbers, the most likely scenario is probably a repeat of Mrs Merkel's 'grand coalition' with the Social Democrats (SPD). Depending on the shape of the coalition, the main issues at stake are the integration of the more than one million migrants, investment at home and Mrs Merkel's role in talks on EU reform and relations with Russia and Turkey.
Conservatives, Social Democrats (Grand Coalition)
The most likely outcome, according to opinion polls. Merkel's parliamentary party, made up of her Christian Democrats (CDU) and the Bavarian Christian Social Union (CSU) has governed with the SPD for eight of the 12 years that Mrs Merkel has been chancellor, including the last four.
However, coalition is a last resort for both sides, especially the SPD, which fears it will lose out as junior partner. It wants more emphasis on investment, education, tackling inequality and fair pensions while conservatives are more focused on tax cuts.
Conservatives, Free Democrats
Merkel's CDU and the pro-business Free Democrats (FDP) are traditional partner. The FDP has rebounded this year, winning enough votes in North Rhine-Westphalia in May to share power with the CDU there. A repeat at federal level would herald tax cuts and deregulation and possibly tighter laws on immigration.
In government the FDP has more radical tax reduction and privatization plans than Mrs Merkel, opposes deeper EU integration and wants countries to be able to quit the euro zone.
Conservatives, FDP, Greens (Jamaica - reference to parties colours of black, yellow, and green)
As yet untested at a federal level, this combination rules in the northern state of Schleswig-Holstein.
If Merkel's bloc can't form an alliance with the FDP or the Greens alone, it may try a three-way deal. Both smaller parties have played down this option but may be lured by the prospect of power.
One potential hurdle is that the Greens and FDP are at opposite ends of the political spectrum. Policy clashes would be likely on tax, energy, the EU and migrants.
Untested at a federal level, this has been mooted as an option under Merkel, who has pushed renewable energy. The CDU and Greens have worked together at regional level, including in a Greens-led coalition in the rich southern state of Baden-Wuerttemberg.
Minority government/new elections
A minority government would be a first and stability-craving Germans would not like it but may prefer it to new elections.
Never tested at a federal level, a tie up between the SPD and Greens, preferred partners, and the radical Left party, could be the only way for the SPD to take the chancellery. Its an outside possibility that would move Germany to the left.