Once the exception, conservative-Social Democratic partnerships are threatening to become the rule in Germany. So how good or bad is this form of government for the country?
The accepted political wisdom in Germany is that so-called grand coalitions are exceptional forms of government reserved for helping the country get through times of emergency. But with preliminary conversations underway between the Christian Democrats (CDU), their Bavarian sister party the Christian Social Union (CSU), and Social Democrats (SPD) about forming what would be the third such alliance under Chancellor Angela Merkel, it's clear that the paradigm has changed.
Merkel and the CDU/CSU have spent more than eight years out 12 in grand coalitions - compared with only four governing with the center-right Free Democrats (FDP).
Grand coalitions aren't usually greeted with great enthusiasm by supporters of either side. Nor is the general public particularly enamored with them. But that doesn't mean Germans are necessarily unhappy being governed by such alliances.
"The grand coalition is not unpopular among the general public," political analyst Hugo Müller-Vogg told DW ahead of Germany's national election on September 24. "Germans crave harmony. They're basically comfortable with a grand coalition."
If so, than Germans have been getting a lot of what they crave in recent years — in contrast to the past, when Germany's political landscape was both a lot more and a lot less contentious.
Merkel: The grand coalition chancellor
From its founding in 1949 to 2005, Germany was usually governed by a coalition led by either the CDU/CSU or the Social Democrats in partnership with either the FDP or, later, the Greens. The lone exception was from 1966 to 1969 when the Germany's two largest parties teamed up in order to overcome economic recession and get the runaway government budget under control.
The situation fundamentally shifted in 2005. Cutbacks to Germany's social benefits system, made under a Social Democratic-Green coalition, led to widespread dissatisfaction on the left. The precursor of today's Left Party entered the Bundestag, adding a fifth player to the parliamentary landscape.
The upshot was that neither the CDU/CSU nor the SPD could form a majority with just one of the smaller parties. The political center was weakened, but the result, paradoxically, was to encourage conservatives and Social Democrats to cooperate. Merkel became chancellor with the votes of her own parliamentary group and those of her primary rivals.
After forming another grand coalition in 2013, the rise of the far-right populist Alternative for Germany (AfD) added a sixth party to the parliamentary arithmetic four years later. A vicious circle may have arisen, whereby grand coalitions create dissatisfaction on the political margins, further undermining the political center and necessitating greater cooperation between Germany's two largest parties.
The pros and cons of a grand coalition
The great advantage of an alliance between Germany's biggest parties is that it allows the government to get basic things done on which there is considerable consensus. Merkel's last grand coalition — the current caretaker government — had a sizable list of achievements: expanding dual citizenship, finalizing Germany's phase-out of nuclear power, establishing a minimum wage, allowing some people to retire at the age of 63 and passing anti-hate-speech legislation.
"In terms of output, it was a completely acceptable result," Uwe Jun, a political scientist at Trier University, told DW. "The grand coalition achieved a lot for the German population."
What grand coalitions don't do very well is set out new agendas on issues on which Germans passionately disagree. Nowhere has this been more apparent than on the topic of refugees.
"The grand coalition made the public feel that its governance was solid and that there was no reason to get upset," political scientist Gero Neugebauer told DW. "Angela Merkel enjoyed steady positive ratings. She only dipped in relation to the refugee crisis where she couldn't explain how Germany was going to be deal with it."
Critics also say that alliances between the two biggest parties weaken the culture of constructive political disagreement and debate and thereby encourage extremist political groups.
"A grand coalition limits the give-and-take between government and opposition, which is one of the main characteristics of a liberal democracy," said Jun.
No other alternative?
Perhaps for that reason, experts aren't terribly enthusiastic about the possibility of two consecutive grand coalitions — especially since both of the partners lost votes in September compared with 2013.
"Nothing more speaks for the formation of a grand coalition right now than it did in September," Neugebauer said, adding that the SPD, in particular, can only lose by prolonging the current arrangement under Merkel. "It's like sending a lightweight into the ring for a heavyweight fight.
The problem for both conservatives and Social Democrats is that the alternatives, a snap election or a conservative-led minority government, are equally unpalatable. Neither promises a revival of the parties' popularity.
Indeed there is a sense at present that Germany has no alternative to another grand coalition and that the great political rivals will once again have to come together for the good of the country, no matter how much it may hurt their own narrow interests. At least conservatives and the SPD can take some solace from the fact that since a grand coalition has been back on the table, perceptions that they are willing to make sacrifices for the national good has led to a slight uptick in their popularity in opinion surveys.