Paul Hockenos is the author of "Berlin Calling: A Story of Anarchy, Music, the Wall and the Birth of the New Berlin." The opinions in this article belong to the author.

(CNN) After six long months of coalition talks, the new German government of Christian Democrats and Social Democrats finally got off to a start two weeks ago -- but it crashed almost at once.

There's an enemy within it: the far-right Alternative for Germany (AfD) , a xenophobic nationalistic party that clambered into the Bundestag for the first time this term. Or rather, the toxic rhetoric of that party has found its way into the coalition.

Of course, the AfD is in opposition , and all of Germany's other parties -- government and opposition -- have vowed to isolate it.

But that's not happening. The far right's noxious populism has seeped into the highest halls of power, even to those surrounding Chancellor Angela Merkel.

In the administration's first week in office, before Merkel had the chance to breathe, members of her own freshly picked (and judiciously lauded) Cabinet started attacking her from the right, using the arguments and jargon of the AfD -- exactly what they agreed to avoid.

The chief culprit was a familiar friend/foe : the new interior minister, Horst Seehofer of the Christian Social Union, or CSU -- which is the conservative sister party of Merkel's own Christian Democratic Union, or CDU.

Since the early postwar years, the CDU and CSU have run on the same national ticket, the difference between them quite marginal, with the Bavarian CSU positioning itself slightly to the right of its big sister, usually on cultural and security policies.

Seehofer demanded, for example, that his ministry be renamed the "Federal Ministry of Interior, Building and Heimat."

Heimat can be translated as "homeland," but it is a very loaded term in German as it was central to Nazi ideology and its ethos of territorial expansion. All Germans in Europe, preached Hitler, belonged within the borders of the German Heimat. This ethnically pure homeland was folkish, seamless and imbued with the essence of Germanness.

Moreover, in the coalition negotiations, the CSU explicitly staked out a harder line on immigration than Merkel, insisting that an upper annual limit -- around 200,000 migrants -- be set on newcomers immigrating to Germany.

Seehofer's CSU also demanded that fewer families of refugees be allowed to join their relatives in Germany. These stipulations were hardly surprising, as Seehofer had frequently and harshly criticized Merkel's handling of the migration crisis in 2015 and 2016.

Yet, despite these gestures to the right, Merkel, her party and the Social Democrats all believed Seehofer and the CSU would abide by their pledge to build a wall between the AfD and Germany's democratic parties.

Merkel had said that Germany's political class should "draw clear red lines" between the country's postwar democracy and the AfD, and try to push them out of the parliament, with substantive responses to their off-the-cuff populism.

But this measured strategy foundered before it even got started.

JUST WATCHED Who is Angela Merkel? Replay More Videos ... MUST WATCH Who is Angela Merkel? 02:15

Seehofer shocked his Cabinet peers with a surprise attack on one of the cornerstones of Merkel's 12-year chancellery. "Islam," he said, "does not belong to Germany," contradicting Merkel's express words to the contrary. "Germany is shaped by Christianity. This includes free Sundays, church holidays and rituals such as Easter, Pentecost and Christmas," said Seehofer.

Muslims living in Germany, Seehofer continued, belonged to Germany . But that does not mean, he said, "that we Germans should, out of false consideration, abandon our national traditions and customs."

Merkel, clearly caught off guard and unhappy, shot back at once that the German government firmly believes that Germany's 4.5 million Muslims belong to Germany as does their religion.

This sentiment, namely that Germany's naturalized newcomers, many of whom are Muslims, are full and equal citizens of Germany, is a strong argument for their integration into Germany. For integration to happen, naturalized Germans of foreign origin have to feel welcome, respected and at home. It was a generous and open-hearted offer to Muslims to join a multicultural Germany as a positive component.

Seehofer's words could have come straight from the mouths of the AfD's leaders. They regularly insist that Islam is a dangerous, foreign, violent ideology that threatens Western Christian civilization and German jobs.

The AfD goes further than the CSU by saying that Islam contradicts German's constitution. It also insists that Germany accept only migrants with high technical skills -- in other words, no refugees at all.

With Seehofer as Heimat minister, the AfD for all intents and purposes has a voice in the executive branch. It's a worst-case scenario just weeks into the new administration, which will be defined by the way it deals with the AfD.

Seehofer's intentions, which, in my opinion, accurately reflect those of the whole CSU, are selfish and shortsighted. The CSU faces a regional election in Bavaria in the autumn, and the AfD is poaching its right-of-center voters.

One of the big surprises in the national election last year was the AfD's strong 12.4% showing in Bavaria. Although the CSU dominated the Bavarian vote as usual, its 40% was down nearly 11% from 2013.

But experts say that it usually doesn't work when conservative parties move to the right to win back voters from the far right. In Austria, for instance, the conservative party's shift to counter the far-right Freedom Party (FPÖ) only prompted the latter's growth -- and acceptance as part of the mainstream.

There is no one recipe to fight insurgent right-wing parties, the historian Frank Bösch told the weekly Der Spiegel magazine. "Historical and international comparisons show that when mainstream parties take a hardline right path, the rightest fringe parties usually grow bigger and don't disappear."

"Merkel's [centrist] strategy is the right one when she wants [the CDU] to win majorities, which obviously she does," says Bösch. Women in particular tend to flee the big-tent CDU when it shifts too far to the right, he says.

As dangerous as most Germans see the AfD's Bundestag debut, they didn't think that it would have such an impact so quickly. The party is more prominent than ever now as the biggest opposition party.

For now, the establishment can only admonish Seehofer and warn off other right-of-Merkel politicos in the CDU and CSU from joining him off-script. Merkel will do what she can to rein in her minister, even though he has in the past shown no signs of compromising.

A break with the CSU, say from the side of the Social Democrats, would topple the young government. This would be a triumph for the AfD beyond its most optimistic calculations.