Last week, the Thuringian parliament in Erfurt elected Thomas Kemmerich state premier. This was not only remarkable because his liberal Free Democrats have only five members in a parliament of 90.

Kemmerich also found support from the extreme right-wing Alternative for Germany (AfD), breaking a taboo in German politics.

Under enormous public pressure, Kemmerich resigned and the surprising election was quickly corrected. But the incident revealed much about the sad political state of Germany: its party system lies in ruins.

No politician bears more responsibility for this than Chancellor Angela Merkel. After 15 years in office, she will leave her successor with a shambles of a democracy. Thuringia is a symptom of a much larger malaise.

If you are unfamiliar with Thuringian state politics (and who could blame you?), here’s a quick recap.

In October, just under two million Thuringians went to the polls. The result was a polarised, hung parliament. The Die Linke (The Left) party, legal successor to East Germany’s communist rulers, reached 31 percent while the AfD achieved 23 percent. Combined, the two political extremes had an absolute majority.

All other democratic parties (Christian Democrats, Social Democrats, Greens and Liberals) scraped together only 40 percent. Crucially, the previous coalition of Die Linke, Social Democrats and Greens no longer had a parliamentary majority.

So, what to do with an election result like this?

In Germany, parliaments need to elect the head of government. But there were no plausible majorities anywhere. Both centre-right parties – the Liberals and the Christian Democrats – pledged not to do any deals with the AfD or Die Linke. The Social Democrats and Greens objected only to dealings with the AfD and for the last few years have been comfortable about formal arrangements with Die Linke (but not at the national level).

The dilemma was acute for the Christian Democrats and its 21 state MPs. From its perspective, the party felt it was choosing between the plague and cholera. The party headquarters in Berlin quickly put a stop to any ideas about supporting Die Linke’s candidate and it certainly would not cooperate with the AfD.

This led to a bizarre showdown in parliament during the election of the premier. In the first and second round of voting, only Die Linke and the AfD nominated any candidates. Neither achieved the necessary absolute majority and about a quarter of MPs abstained – presumably Liberals and Christian Democrats.

A simple majority was enough in the third round of voting. And then the unthinkable happened. The Liberals unexpectedly nominated their party leader Kemmerich; the AfD did not give its own candidate a single vote; and so Kemmerich was elected with one vote ahead.

Kemmerich not only accepted the election, but also the congratulations of the head of the state AfD – although “AfD Führer” might be more appropriate here, since he likes to talk in the style of the Nazis and may even be, by court order, legally called a fascist.

Chaos broke out in political Germany. Spontaneous demonstrations sprung up across the country and Liberal politicians even received death threats. The federal party leaders of the Christian Democrats and Liberals then instructed their colleagues in Thuringia to correct the election, never mind that Kemmerich had renewed his vow not to cooperate with the AfD.

Meanwhile, during a state visit to South Africa, Chancellor Merkel declared the election “unforgivable” and demanded it be revoked. She even fired one of her junior ministers who tweeted congratulations to premier Kemmerich.

Interventions like these are almost as outrageous as Kemmerich’s election. In a federal system, the national leaders or the federal government should play no role in state politics. Yet everyone and their dog was wading into Thuringia’s affairs leading to Kemmerich’s resignation.

The situation escalated into a farce. Now Die Linke is demanding the Christian Democrats vote for its candidate in return for clearing the path towards a new election. The Christian Democrats might even do that. But having already voted alongside both extremes in one parliament, the party should expect a hammering in the ensuing re-election.

It is hard to blame the Thuringian Christian Democrats for this. The real responsibility lies with Merkel who, for over 20 years, has led her party into this catastrophe. Since becoming party leader in 2000, she has consigned her party to arbitrariness.

Initially, Merkel presented herself as a liberal, but after the narrow federal elections in 2005, she copied Social Democratic and Green positions. This decimated the Social Democrats while her courting of the Greens only caused them to fly higher in the polls. Merkel shifted the entire political spectrum to the left and the right-wing populist AfD thanked her by establishing itself far to the right. The AfD now holds seats in all 16 state parliaments and the Bundestag.

The result is a political landscape in which the formerly dominant popular parties have retreated. The Social Democrats have slipped almost into single digits territory and the Christian Democrats are a shadow of their former selves. In East Germany, the AfD and Die Linke now set the tone.

Merkel has gutted her Christian Democrats so much that their agenda is unrecognisable. It has become a party that elects a prime minister supported by right-wing extremists and would support a post-communist premier. But it still wants to cooperate with Liberals, Greens and Social Democrats at the federal and state levels. Such a party stands for everything and nothing.

Thuringia displays the dramatic consequences of two decades of Merkelism: a party that has no deeply held beliefs and turns with the wind of opinion polls simply cannot create certainty, reliability or predictability – let alone lead a country.

Merkel has led Germany's democracy into a nihilistic vacuum, now being filled by extremes on the left and right. Along with her questionable course of action in energy policy, European matters and migrants, this will be her lasting legacy.

When Merkel finally leaves the political stage at the end of her chancellorship, her party and country will need a long time to recover.