BERLIN — As the euro crisis is in its fifth year, one of the worst nightmares for many in Europe may yet come true. The founding congress of Alternative for Germany (AfD) two weeks ago marks the emergence of a party that wants to exit the euro and challenges Germany’s pro-European political consensus. This has had instant reverberations as Germany heads for national elections. More worrying, however, this is the strongest signal yet that support for Europe and its ailing currency among Germans may be wearing thin.

Few would have thought this movement had legs when in July of last year, 172 economists signed an open letter to protest what they considered to be the German government’s misguided policy of “socializing debt” in the euro zone. Within months, these professors were joined by disgruntled members of the governing Christian and Free Democrats, defining the emerging movement’s clear anti-euro stance and declaring its political ambitions. AfD scored its first success when voters in a key regional election in January dealt a defeat to Angela Merkel and catapulted the protest initiative into the limelight. In the weeks since, regional branches have sprung up across the country, membership in the party has soared to 7,500, and polls suggest potential support from up to a quarter of all Germans. In most EU countries, similar euroskeptic formations emerged soon after the crisis began. While Germany had seemed immune to this kind of populism, the AfD has shattered that illusion. As is true elsewhere in Europe, its program is a crude mix of general demands ranging from an end to political correctness and more direct democracy to a simpler tax regime and stricter immigration laws. It openly flirts with the fringes of German politics to the right and left, but is also aiming to recruit from the strong social and political center where disappointment with the political establishment, feelings of social injustice, and unease with the government’s handling of the euro crisis have all been gaining ground.

This emergence of the AfD changes the playing field ahead of September’s elections for the Bundestag, Germany’s legislature. Until now, the governing coalition of conservatives and liberals were neck and neck with the opposition Social Democrats and Greens. Pundits considered it likely that the considerable popularity of the chancellor, combined with the inept campaign of her challenger, would tip the balance in favor of the current government. According to most observers, the arrival of the AfD will be primarily at the expense of the governing coalition and could even spell the end of Merkel’s chancellorship. However, polls indicate that among the parties’ own voters, 15 percent of Social Democrats and 27 percent of Greens can imagine voting for an anti-euro party such as the AfD. This means that across party lines, and among Germans at large, there exists residual reticence about the euro, whose protracted crisis has only nurtured nostalgia for the Deutschemark. The AfD will therefore be a force to be reckoned with by all of the established parties, and will affect the coalitions they might form in the wake of the election and the European policies they propose as part of their campaigns. The political shakeup that the AfD would represent must not be underestimated. German governments, whatever their color, must not allow the AfD to derail the committed, if oft-criticized, pro-European course of the country. They must, however, become a lot better in explaining to the public the benefits of a strong Europe, and especially how the euro is crucial for the economic development and well-being of Germany, its largest economy. For their part, German voters, whichever their affiliation, should think twice about rewarding the AfD at the ballots for what amounts to slogans. They should take pride in the fact that for decades, political rabble-rousers have not stood a chance in Germany, which is one of the most stable and predictable democracies in Europe. Decision-makers and publics elsewhere in the EU will have to consider more carefully how their conduct and criticism of Germany is perceived by Germans.

Through renewed efforts at reform and by shunning the use Nazi clichés, leaders in other EU states can help pull the rug out from under the AfD. But absent a concerted and determined effort by Germans and all Europeans to refute AfD’s populism and consign it to political no-man’s land, the crisis in Europe may just have taken another turn for the worse.

Joerg Forbrig is a program director and analyst with the German Marshall Fund of the United States in Berlin.