A purge of the police, a power struggle with the judiciary and a widening corruption scandal are coming together in a toxic mix for Turkey's half-century-old ambition to join the European Union.
The crisis engulfing Prime Minister Recep Tayyip Erdogan is sharpening suspicions in Europe about the risks of authoritarianism and instability in this linchpin country.
It was way back in 1963 when Turkey and the then European Economic Community signed an association pact, sketched as the first step towards Turkish membership of the European trade bloc.
Negotiations on full-blown accession were eventually launched in 2005, but progress has been meagre. Out of 33 issues where Turkey has to make constitutional, legal, commercial or administrative reforms to align with EU standards, only 17 have been considered satisfactory. The others, including guarantees of the independence of the judiciary and freedom of the press, are either still being haggled over or have been frozen, in some cases for years.
Officially, both sides insist they are keen on a marriage. After overcoming German objections, the EU's executive commission restarted negotiations on one of the issues last November.
"The EU accession process is the most significant modernisation project of Turkey after the proclamation of the Republic," Turkish EU Affairs Minister Mevlut Cavusoglu said, referring to the founding of post-imperial Turkey in 1923 by the secularist Kemal Ataturk.
Erdogan is to visit EU headquarters in Brussels on January 21 - his first since 2009. French President Francois Hollande is due to start a state visit to Turkey on January 26.
Beneath the surface, though, things are different. To many Turks, the EU has become less attractive because of its economic problems and currency turbulence. Europe, meanwhile, is worried by Erdogan's populism and strongman image.
Alarm bells rang last June when the Government cracked down on street protests triggered by plans to build on Gezi Park, a public space in central Istanbul. Six people were killed, 8000 were injured and more than 250 were charged, 36 of them with terrorism.
According to a New York-based watchdog, the Committee to Protect Journalists, more journalists are in jail in Turkey than in any other country, including China. It lists 40 journalists behind bars, or nearly a fifth of the worldwide total. Six were jailed last year for life on charges of belonging to a banned group, the Marxist-Leninist Communist Party.
In December, Erdogan went on the offensive against the judiciary after some of his key allies, including high-profile businessmen and the sons of former ministers, were arrested in a corruption probe linked to construction projects and illegal money transfers to sanctions-hit Iran.
To masses of supporters, Erdogan denounced the arrests as a plot to weaken his Government and undermine his influence in the Middle East that would be smashed. He points the finger at a former ally, a US-exiled cleric called Fethullah Gulen, whose organisation wields influence in the police and judiciary. Since December 17, Erdogan has purged hundreds of police officers, sacked dozens of police chiefs including the deputy head of Turkey's national force, and sidelined a public prosecutor who had been poised to order a second wave of arrests, reportedly including the Prime Minister's own son. His Cabinet also ordered police officers to inform their bosses before launching investigations requested by prosecutors - a move seen by critics as a bid to stifle the probe. Turkey's top court blocked the decree.
The EU commissioner for enlargement, Stefan Fule, ripped into the Cabinet order, saying it "undermined the independence of the judiciary and its capacity to act". He pointedly urged Turkey, "as a candidate country committed to the political criteria of accession", to ensure that allegations of wrongdoing were addressed transparently and impartially.
Yesterday Erdogan's AKP party went further and began moves to allow the Government a veto over the appointment of judges and prosecutors.
The European Commission responded by expressing concern at the erosion of judicial independence and called on Turkey to uphold commitments to law and justice.
"We urge Turkey, as a candidate country committed to the political criteria of accession ... to take all the necessary measures to ensure that allegations of wrongdoing are addressed without discrimination," a spokesman for the European Commission said in Brussels.
"Turkey appears to fall behind the EU political criteria when it comes to issues like media freedom, freedom of expression and, now, an independent judiciary," said Ozgur Unluhisarcikli, Ankara director of the think-tank the German Marshall Fund of the United States.
"The Government's responses to the Gezi Park protests and to the recent corruption probe have visibly tarnished Turkey's image in the EU. [This] will undoubtedly prevent its EU accession process gaining a real momentum."
The turmoil has also affected Turkey's reputation for stability and prosperity, which was one of its biggest pluses in Europe.
Suddenly weakened, Erdogan has been forced into a Cabinet reshuffle and defections from his Justice and Development Party (AKP), five of whose legislators have quit. Among the sacked ministers was EU Affairs Minister Egemen Bagis, who had been chief negotiator for Turkey's EU membership.
Municipal elections loom in March, providing a potential battleground between the AKP, which has its roots in Islamism, and Turkey's secular parties. The lira has plumbed record lows against the dollar and share values have tumbled on the Istanbul stock exchange. The Government variously estimates losses to the economy at US$50 billion or $100 billion.
"In Turkey's political environment, a strong economic performance is essential to ensure the acceptance of the government," Emre Erdogan, of Istanbul's Infakto Research Workshop told Reuters.
"As it becomes more difficult for the government to demonstrate this, things start to get more unstable and unpredictable," Erdogan, no relation to the Prime Minister, added.
Even if it carries out reforms to the satisfaction of the European Commission, Turkey still has to overcome political hostility in Greece over Turkish colonisation of northern Cyprus, as well as quietly-voiced reservations in France and Germany about admitting 74 million people, most of them Muslim, whose country geographically lies mainly in Asia.
"In the present situation, the chances of Turkish membership of the EU in the coming years seem to be negligible," said Dr Karol Kujawa, of Canakkale Onsekiz Mart University.
Elected in 2002 after a decade of unstable coalition governments, Erdogan at first used the accession issue as a "life insurance" against a feared coup by the military, the self-appointed guardians of Turkey's secular constitution, said Kujawa. But as Europe's ambiguity about membership became clear and Turkey's economy grew, Erdogan's focus shifted to transforming the country into a regional power, he said.