Emily Schultheis is a writer based in Berlin with a fellowship from the Institute of Current Affairs. Her reporting on the rise of the far right has appeared in The Atlantic, Foreign Policy and Politico, among other publications. The views expressed here are her own. Read more opinion at CNN.

BERLIN (CNN) It only took one vote in one state parliament for Germany's populist far right to break a decades-long political taboo, topple Chancellor Angela Merkel's chosen successor and trigger a political crisis whose implications reach even beyond the country's borders.

Emily Schultheis

The action by the Alternative for Germany, or AfD, in the eastern German state of Thuringia earlier this month—where the party voted with two centrist parties, the Christian Democrats and the Free Democrats, to help oust the state's left-wing prime minister—shattered traditional parties' long-standing refusal to cooperate with the far right, either formally or informally.

That this occurred in Thuringia, which was the first state in which the Nazi party gained its political foothold in 1930—and also the state where the AfD is led by the party's most notorious far-right figure, Björn Höcke —exacerbated the sting of the vote in a country still deeply conscious of and affected by its Nazi past. ("A pact with fascism!" cried one headline; Merkel, traveling on a state visit in Africa at the time, called it "a bad day for democracy" and said the decision was "unforgivable.")

The consequences were swift: The FDP's Thomas Kemmerich, the man elected with AfD votes, resigned the day after the vote. In response to criticism of her handling of the situation and inability to control her state-level CDU colleagues, Annegret Kramp-Karrenbauer, Merkel's self-anointed successor and head of the party, also resigned her post; the direction of her party, and therefore the country, now depends greatly on who succeeds her.

What's more, the whole situation threatens the stability of the current national government under Merkel, a cooperation between the CDU and the center-left Social Democrats. Germany, in other words, went from at least the appearance of political stability to relative political chaos in a matter of days.

Read More