Buoyed first by a Greek debt crisis and then by an unprecedented influx of refugees to Europe, the rise of Germany’s rightwing populist Alternative für Deutschland party has at times looked inevitable, leading one politician recently to predict a “total victory” for his party in the coming federal elections.

With less than seven months to go, however, the AfD engine is suddenly sputtering. Over the past week, three separate polls have shown support for the party slip below 10%, down from a record high of 15% last September.

The slump is taking its toll on the party chiefs. On Friday, German media reported that party members were gathering signatures to force a new vote on their leadership, currently shared between Frauke Petry and Jörg Meuthen.

While the AfD has continuously outperformed pollsters’ estimations in the past, and entering parliament would represent a triumph for a political group formed only three years ago, observers say it is hard to see how the party’s troubles could easily resolve themselves before September.

The AfD’s current crisis was triggered in mid-January through a taboo-breaking speech by the rightwinger Björn Höcke, who in a beer hall in Dresden called for a “180 degree turn” in Germany’s culture of remembering and atoning for the Nazi era.

In the month since, the party has dithered over whether to expel Höcke for his comments, revealing a broader division about the group’s future direction.

Petry appears intent on modelling the AfD on France’s far-right Front National, whose leader, Marine Le Pen, attended a summit of European “new right” parties in Koblenz organised by Petry and her husband, Marcus Pretzell, shortly after the Höcke speech.

Copying Le Pen, who has attempted to soften the image of the FN, would require a symbolic break with nationalist and antisemitic elements in Petry’s party, which may have convinced the 41-year-old of the need to cut ties with the Höcke.

But other politicians in the AfD, such as the deputy leader, Alexander Gauland, see their party’s future as distinct from that of other European populists groups such as the FN, Austria’s Freedom Party or Britain’s Ukip. To get enough votes in Germany, they argue, the AfD requires not one charismatic leader but several faces, appealing to both nationalists in the former east and economic liberals in the country’s wealthy south west.

The divisions have led one newspaper, Sächsische Zeitung, to ask: “Is the AfD about to split?”

Ironically, both camps accuse each other of drifting off to the far right, either by being too soft on Höcke or by not distancing the party from the Front National.

Melanie Amann, a journalist for the weekly Der Spiegel and author of Angst für Deutschland (“Fear for Germany”), a forthcoming book on the AfD, said the Höcke scandal had ended up hurting the party’s fortunes in more ways than one.

“On the one hand, the speech genuinely shocked economic liberals who believed that the AfD is at heart a version of the Christian Democratic Union before Angela Merkel moved them to the political centre. On the other hand, the threat of expelling Höcke for his comments has alienated the party’s far-right nationalist support.”