When Angela Merkel stepped on to the podium at her party headquarters on Sunday night to announce she would run for a fourth term in 2017, the message the German chancellor projected to the outside world was that, in a world of political upheavals, she would remain a constant.

Yet the internal party debates that culminated in her announcement have made one thing clear: if Merkel wants to match the records set by her predecessors Konrad Adenauer and Helmut Kohl and be elected to a fourth term in office, much will need to change.

According to a poll published on Sunday by the Bild newspaper, 55% of Germans want to see Merkel remain in office, up from 42% in August. Eleven years into her leadership, her approval ratings are higher than those even of populist regimes.

Rightwing populists

Supporters of Pegida, the anti-immigration rightwing movement, march through Dresden last year. Photograph: Fabrizio Bensch/Reuters

But the social climate in Germany has changed considerably in the three years since Merkel’s Christian Democrats won the election with an overwhelming 40.5% of the vote. A new rightwing populist party is on the rise. Many blame her move to the centre ground for having destroyed the country’s political landscape.

The chancellor implied as much when she said her party would have to “fight off attacks from all sides” – a new experience for a party that used to make a principle of not allowing rivals to gain a profile to their right.

A draft strategy paper leaked to the German press over the weekend suggested the chancellor would try her utmost to avoid the numbers of refugees arriving in Germany to reach the crisis levels of 2015, while at the same time not committing herself to an upper limit.

It also said she would try harder to address “the losers of modernisations” while resisting populist rhetoric – a delicate balancing act.

Coalition partner woes

From left: foreign minister Frank-Walter Steinmeier, chancellor Angela Merkel, Social Democrats chair Sigmar Gabriel and his Bavarian Christian Democrats counterpart, Horst Seehofer, arrive at the Bundestag in Berlin. Photograph: Sean Gallup/Getty Images

Senior party members who were present at Sunday’s meeting said there was at the very least an agreement in the room that Merkel would not be able to win another election with the kind of apolitical feel-good campaign the CDU ran in 2013, and that the party would need to distance itself from her current coalition partners, the Social Democrats, on themes such as economic stability and personal wealth – at least for the duration of the campaign.

Behind closed doors, politicians on the centre-right and the centre-left concede that another “grand coalition” between their parties is mathematically the most likely outcome and the most responsible decision in a globally unstable environment, even if it risks fuelling anger at the political establishment.

A coalition government between Merkel’s CDU and the Green party, much talked-about only a year ago, looks increasingly fanciful, and not just after Donald Trump’s victory in the US. Observers say a conservative coalition government with a Green junior partner would descend into infighting amid calls for Germany to take a more active military role.

A 2017 victory for rightwing upstarts Alternative für Deutschland, as much as it would fit a pattern set by Brexit and Trump’s win, is not worth serious consideration. Apart from a few minor MPs in the Christian Democrat’s Saxony branch, Merkel’s party has been as unequivocal in ruling out a coalition with the AfD as more leftwing parties.

Absolute majorities are extremely rare in German politics – Adenauer achieved the last one in 1957. In 2013 the Christian Democrats missed out on an absolute majority by only five seats, partly because a high number of votes went to parties that did not make it above the 5% threshold required for entering parliament, meaning 43% of the vote would have been enough for the CDU to rule on their own.

In 2017, that proportion is expected to be higher, since current polls see up to six parties entering parliament. With the AfD currently on between 10-14% in the polls after an unprecedented influx of asylum-seekers and the first Islamic State-inspired attack on German soil, a Trump-esque upset would still require them to triple, if not quadruple their support.

The red-red-green threat

A migrant from Syria holds a picture of Angela Merkel as he and approximately 800 others arrive from Hungary at Munich railway station. Photograph: Sean Gallup/Getty Images

If a political obstacle emerges on Merkel’s path to a fourth term, it is more likely to come from Berlin – not her chancellory or the parliament next door, but the Berlin senate, where the Social Democrats, the Left party and Green party have just agreed on a coalition government to run the capital’s affairs for the next five years. If their collaboration proves a success, some commentators say, it could provide inspiration for the three parties to campaign on a joint ticket in 2017.

In 2013, the three left-leaning parties earned enough votes for a theoretical majority but were unable to put aside their historic differences, particularly on foreign policy issues. Three years later, with a “red-red-green” or “R2G” government functioning without major incidents at state level in Thüringia, and a working group having first at the Bundestag in October, the mood is more positive.

Christian Lange, a Social Democrat state secretary in the justice ministry, recently called on his party to learn from Portugal, where prime minister António Costa managed to create leftwing minority coalition government with the Communist and Marxist parties by bracketing out foreign policy hot potatoes such as the euro, Nato and military interventions.

Doing so with a self-confident German Left party might, however, be more tricky. As recently as June, Die Linke tabled a motion for Germany to leave Nato and replace it with “a collective system for peace and security in Europe that includes Russia”.

Whether Germany’s Social Democrats are prepared to risk breaking with a chancellor who has many admirers in its ranks in order to pursue such a precarious path depends largely on their candidate – with deputy chancellor Sigmar Gabriel and the president of the European Parliament, Martin Schulz, the most likely contenders.

If the nomination of foreign minister Frank-Walter Steinmeier is anything to go by, yearning for stability is likely to overcome any taste for adventure. And Merkel will have little to prevent her from re-entering the chancellery, once again, in 10 months’ time.