Sept 23 (Reuters) - Germany faces months of tough negotiations to form a coalition government after the federal election on Sunday, with three parties set to need to team up to clear the threshold of 50% of all seats in the Bundestag after the vote.
Here is a summary of the most likely coalitions and some of the compromises that will be necessary to reach agreement.
"TRAFFIC-LIGHT" (SPD, Greens, FDP)
If Olaf Scholz's centre-left Social Democrats come first, the Greens, now third in polls, would be his obvious choice for a coalition partner. The parties broadly agree on environment policy and on raising taxes and social spending, though the Greens are far more hawkish on Russia policy.
But if the SPD is to reclaim the chancellery for the first time since 2005 they will also need to get the liberal Free Democrats on board to form a traffic light coalition, so-called due to the party colours of red, green and yellow.
FDP leader Christian Lindner has sounded cool on the possibility, saying legalising cannabis is about the only thing his party could easily agree with the SPD and Greens.
While the liberals are far to the right of the SPD and Greens on economics, they might compromise if it meant keeping the far-left Linke, loathed by many of their voters, out of office, and if it means they win control of the Finance Ministry.
Probability: 45% according to the Eurasia group
JAMAICA (CDU/CSU, Greens, FDP)
Armin Laschet's Christian Democrats would prefer to team up with the FDP. "Christian Liberal" governments ran Germany for much of the post-war era, and the two are closely allied on economic policy.
But the two parties are unlikely to have enough seats to govern alone. So they could ask the Greens to form a Jamaica coalition - the parties' colours of black, yellow and green make up that country's flag.
However, such an alliance will also not be easy: liberal leader Christian Lindner unexpectedly pulled out of talks on forming a Jamaica coalition in 2017.
On environmental policy the Greens and the FDP are far apart, while both the conservatives and the liberals are significantly more hawkish on defence spending.
Probability: 30% according to the Eurasia group
GRAND COALITION (CDU, SPD or CDU, SPD and Greens)
The SPD has been a reluctant junior partner to Merkel's conservatives for 12 of the past 16 years. They have ruled out working together again, but said the same at the election in 2017, and ended up agreeing when other options failed.
Probability: 10% according to the Eurasia group
"RED-RED-GREEN" (SPD, Linke, Greens)
If the SPD and Greens fail to team up with the FDP, the conservatives have raised the spectre of a "red-red-green" coalition with the hard-left Linke party, heirs to the Communist Party that ruled East Germany. read more
The SPD and Greens have also ruled out working with any party refusing to commit to the NATO military alliance or Germany's European Union membership, both of which the Linke has called into question.
The Linke could fall below the 5% threshold needed to enter parliament, but is likely to win three constituencies directly, meaning it would still contribute enough seats to a left-wing coalition to reach a majority.
Probability: 5%, according to the Eurasia group
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