This is how it could all go wrong for Angela Merkel in the German elections

There is a comforting view of the German general election according to which Angela Merkel and her centre-right alliance are set fair for re-election and the German ship of state will sail serenely on. So dominant and so trusted is Merkel, this version goes on, that it hardly matters which party she invites to join her in the inevitable coalition. Germany, Europe and the world are in for four more years of pretty much the same.

So here, for argument’s sake, is what could go wrong, if not now, then in what looks likely to be Angela Merkel’s fourth and final term as Bundeskanzlerin.

First, could she lose? It looks highly improbable. But losing in a German election, because of the way the electoral system works, is relative. Emerging as the largest party, her centre right CDU and its Bavarian CSU ally would have the right to try to form a coalition first (and all polls give them a double-digit lead). But this prospect could be upset in several ways.

It is will not be known until the results are in how much – if any – support the far-right Alternative für Deutschland (AfD) party has taken away from Merkel. Germans are reticent, for obvious reasons, about acknowledging any xenophobia, and many Germans say they are proud of the generosity Merkel, and Germany, showed during the refugee crisis two years ago. But that sympathy is by no means universal. Outdoor rallies in town squares are a feature of German elections, and Merkel was repeatedly whistled and booed when she defended her decisions, especially when she spoke in the former East. Much of that hostility was orchestrated, but could it translate into votes that eat into her party’s lead?

She has made clear that a coalition with the AfD is out of the question. But could larger-than-forecast support for that party, or a poorer-than-expected result for the centre-left SPD, leave her unable to form a governing coalition – either a “grand” coalition, as now, with the SPD, or a centre-right coalition with the free-market FDP?

In that event, might the SPD have a chance to form a three-party coalition of the left, including perhaps the further-left Die Linke (if they gain more seats than expected) and the Greens? This is not thought likely. The SPD has run a disappointing campaign, despite having seasoned ex-European Parliament Speaker Martin Schulz at its head. But his theme of social inequality, plus his more sceptical approach to migration, has struck a chord. The arithmetic on Sunday night could prove complicated. Nothing can be completely ruled out.

Let us grant, though, that Merkel is able to form a coalition, either with the FDP, as she appears to favour, or with the SPD, as the amicable mood of her televised debate with Schulz suggested was entirely possible. In either case, though – and this is the second assumption that could prove wrong – there is no guarantee whatsoever that a new Merkel government will be more of the same. A coalition with the FDP could push foreign policy in a more hawkish, security-orientated direction, and domestic policy towards a more market-orientated approach.

Even a new “grand” coalition would not necessarily be more of the same, as Schulz is seen as more doveish on Russia, for instance, than either the current foreign minister, Sigmar Gabriel, or his predecessor, (now German President), Franz-Walter Steinmeier, leading lights for the SPD in Merkel's two "grand" coalitions.

Not only this, but the election of Emmanuel Macron in France, coupled with Brexit, has given new energy to idea of a French-German core driving closer European integration. There are different ways in which this could eventually work out – including a two-speed Europe determined by a more powerful central bank and who is in or out of the euro. But from taking a low-key largely managerial role, Germany could find itself representing the case for greater cohesion in tandem with France.

Not only may Merkel’s fourth government, then, not be more of the same, but – in the third assumption that needs to be challenged – it could face a rougher ride in the German parliament than before. If Merkel’s coalition is with the FDP, then the centre-left (with or without Schulz at its head) becomes the official opposition. What is more, with a campaign pitch of Germany’s increasing inequality and the difficulties that the country could experience in integrating its one million or so new arrivals, a centre-left opposition could have a persuasive case to make, and Schulz – experienced Euro-Parliamentarian that he is – could be the person to make it.

Even if the SPD goes into a “grand” coalition, however, opposition in the Bundestag could well be more forceful and a lot more energetic than before. Polls suggest that all four smaller parties could reach the 5 per cent threshold for recognition as party groupings in parliament. They range from the anti-migrant AfD and the FDP on the right, to the Greens and Die Linke on the left. In what may be a harbinger of things to come, their – mostly young – leaders faced off in an unusually lively and varied television debate, but also showed that there could be potential for building ad hoc alliances to frustrate some government plans.

And so to the fourth element that could go wrong . Merkel’s own CDU-CSU alliance experienced something of a wobble in its third term, mostly over migration. One reason there was no revolt and the alliance stabilised was the lack of any challenger. This could change. Once she embarks – if she embarks – on her fourth term, there will be a clear sense (whether she says so or not) that this will be her last term as Chancellor, and the jockeying for the succession will begin. She has no obvious heir, and her recent dominance of her party has been such as to preclude any serious rival emerging. Sundry favourites for heir have come and gone, discredited by some scandal or other.

In four years’ time, however, if not before, the CDU is going to need a new leader. Will Merkel have the luxury of bowing out gracefully with an approved successor in place, or will her last administration be weakened by the struggle for her throne? Could she even be deposed by someone as opportunistic and ruthless as she proved, when she deposed her one-time mentor and the father of German unity, Helmut Kohl?

One possible contender is the former defence minister Karl-Theodor zu Guttenberg, who resigned in 2011 over a plagiarised thesis but re-appeared on the campaign trail this autumn to acclaim for his oratory and political presence. Whether he will be able to allay the doubts about his integrity and return to government is not yet clear. Others will surely step forward.

Whatever happens, and however it happens, it would be distasteful to see infighting or a revolt of the sort that felled Margaret Thatcher devalue Angela Merkel’s last term in office. Her past – between her father’s vicarage and the East German system – and her worldview as a post-Cold War secular Christian Democrat – made her the ideal Chancellor for her time. Let’s hope that the same acute sense of timing that propelled her to the top of German politics allows her to make a dignified departure.