Turkish President Recep Tayyip Erdogan's narrow victory in a referendum to strengthen his powers is likely to swiftly test his already worsening relations with the European Union.
Erdogan said on Monday that Turkey could hold another referendum on its long-stalled EU membership bid -- and a further plebiscite on re-introducing the death penalty, a red line for the bloc that would exclude Ankara's candidacy.
Sunday's referendum on expanding Erdogan's powers came almost exactly 30 years after Turkey formally applied -- April 14, 1987 -- to join the EU.
Esra Ozyurek, an associate professor at the European Institute of the London School of Economics, said the fact that Erdogan had spoken so swiftly on the death penalty was an important indication.
"If he thinks that his anti-European language gains him votes, and nationalism definitely increases his vote, he may go with it," she said, noting Erdogan said such a step was "the first thing" he'd do next.
The Turkish strongman, however, did not get the unanimous outcome on Sunday that he had sought -- a slim majority of 51.41 percent voted to hand him boosted powers.
The vast majority of the constitutional reforms will follow a presidential election in 2019.
Ibrahim Dogus, founder and director of the Centre for Turkey Studies think-tank in London, said if Erdogan is to galvanise his supporters "he has to go harder and harder... on issues like the death penalty."
The referendum campaign was marked by virulent Erdogan invective against the EU and its leading states, accusing Germany of behaving like Nazis by banning numerous rallies by his ministers hoping to whip up the 'Yes' vote among expatriate Turks.
- End of the dream? -
Marc Pierini, a visiting scholar at Carnegie Europe focused on Turkey and the Middle East, said bringing back the death penalty would allow Erdogan to pin the blame on the EU for the end of the membership bid.
"Bringing back the death penalty would have two objectives: putting an end to any internal disagreement, and triggering a formal halt by the EU -- and not by Turkey -- of the accession negotiations," Pierini said.
Germany and France have both warned Turkey about the broad consequences of reinstating the death penalty, which was abolished in 2004.
German Foreign Minister Sigmar Gabriel said that if Ankara were to bring back capital punishment, the move would be "synonymous with the end of the European dream" and mark the end of decades of talks to enter the EU.
- 'Even more difficult' -
The referendum result and Turkey's difficult relations with the EU mean the two are "on a collision course", according to Amanda Paul, a Turkey specialist at the European Policy Centre in Brussels.
"I don't think it's going to make him more cautious vis-a-vis the EU, particularly because the result was so narrow," she said of Erdogan.
"We'll probably continue to see what we've been seeing for the past few months, a pretty anti-EU narrative, he's not going to change this."
Although the accession progress "has been dead for a long time", officially drawing it to a close would have longer-lasting implications domestically and abroad.
"They're going to be caught in an even more difficult situation now because clearly the nearly 50 percent of Turks that voted 'no' will be expecting the EU to continue to engage with Turkey, not to close the door on Turkey," Paul said.
"But I'm guessing a number of member states and possibly the European Parliament will be pushing for an official freezing of the accession process.
"I personally believe that a relationship between Turkey and the EU that is just based on economy and trade will be a significant blow to Turkish democrats and those that support reform and the modernisation of the country," she added.
"It's certainly not going to do them any favours. Furthermore if the EU continues to turn a blind eye to the democratic deficits in Turkey, what does it say about the EU as a value based actor?"
The most intransigent Europeans, such as Austrian Foreign Minister Sebastian Kurz, have already called for an end to accession negotiations.