The road link between Greece and Macedonia has never looked better. Newly tunnelled, cemented, widened and signposted, it winds through rolling hills, past vineyards and villages and wood-covered slopes all the way to Skopje, the former Yugoslav republic’s capital.

The European Union takes great pride in this. At a time of impoverished connections between the two bickering Balkan neighbours, the newly paved route is concrete proof of what progress and prosperity can achieve. Every few miles a billboard proclaims it is the EU that co-funded the road’s “rehabilitation”.

When Macedonians vote on Sunday in a referendum that could result in changing their country’s name – and resolving a decades-long dispute with Greece – Brussels hopes it is projects like this that will sway their ballots.

A yes vote would not only see the tiny state being renamed North Macedonia but would clear the path to membership of Nato and the EU. As the military alliance’s 30th member, the landlocked republic, which came close to inter-ethnic conflict in 2001, would secure the stability and security it has long craved in a region prone to shifting borders and bloody strife.

For Petre Shilegov, the mayor of Skopje, the choice is a no-brainer. “It’s very simple. Either we become North Macedonia or North Korea,” he says with strident emphasis in his airy single-storey office. “Our opponents have no plan B. They can only offer isolation.”

With Macedonians facing record unemployment, economic stagnation and few prospects, the referendum offers a once-in-a lifetime opportunity to move forward. “The EU spends approximately €260,000 per day supporting Macedonia,” Shilegov explained. “If we have a yes, that sum will increase and everything in our country will get better – in our schools, in our hospitals, on our streets.”

The high-stakes vote follows a landmark accord struck with Greece in June, almost 27 years after the republic seceded from Yugoslavia and declared independence.

Under the deal, signed on the banks of Lake Prespa by Skopje’s social democrat prime minister, Zoran Zaev, and Athens’ leftist leader, Alexis Tsipras, Greece pledged to lift objections that have thwarted the nation’s EU and Nato integration on condition that the state agreed to amend its name by adding a geographical qualifier and dropped any claim to cherished Greek cultural figures including Alexander the Great.

Athens has argued with vigour that unless distinguished from the adjacent Greek province of Macedonia, the republic’s nomenclature would forever imply thinly disguised territorial ambitions towards a region that includes the strategic warm-water port of Thessaloniki.

Greeks, in return, have had to accept their neighbours as internationally recognised Macedonians who speak the Macedonian language even if, as Slavs, they bear no relation to the ancient Macedonian warrior king.

On Sunday, Macedonians will be asked if they endorse the agreement once and for all.

“We are very lucky to have had Zaev and Tsipras on both sides,” enthused Sasho Ordanovski, Skopje’s preeminent political commentator. “Macedonia has been a rare success story of peaceful coexistence in the Balkans,” he said of the ability of the country’s Slavic Orthodox majority and Muslim Albanian minority to live together harmoniously. “But membership of the EU and Nato will enable us to finally secure the liberal consensus to guarantee this model of multi-ethnic, cultural, multi-religious democracy.”

At the heart of the Balkan peninsular, Macedonia has long been viewed as a potential powder keg with the strength to ignite a major regional conflagration, which is why the German chancellor, Angela Merkel, Nato’s secretary general, Jens Stoltenberg, and the US defence secretary, James Mattis, have all descended on Skopje in recent weeks to back the name deal and cheer Macedonians on. “Suddenly it is as if our country is at the centre of the world,” Shilegov smiled, listing the high-profile visitors one by one. “This vote is too important to fail.”

Government officials and western diplomats animatedly predict that the plebiscite will pass. But, as in Greece, the compromise it entails has elicited ferocious nationalist opposition. Until campaigning officially ended at midnight on Thursday, protesters such as Goran, in a baseball cap and floppy jacket, were handing out leaflets in Skopje’s central square exhorting pedestrians to boycott the referendum.

In an atmosphere described as both febrile and calm, anti-agreement propaganda has proliferated. By the eve of the vote the republic’s myriad “fake news” farms – infamous for the role they played in disseminating disinformation before the 2016 US elections – had reportedly gone into overdrive, with opponents making widespread use of social media in an effort to suppress voter participation. Decrying the deal, President Gjorge Ivanov has urged Macedonians to boycott the referendum.

Some 1.8 million citizens are eligible to cast ballots but a massive exodus of young people in search of work means confusion abounds as to how many are still in the country. “At least 15% of the voter list are not physically present but they still contribute to the threshold of 50%,” said Marko Trostanovski, who heads the Institute for Democracy thinktank in Skopje. “In reality we have to hit a threshold of 65% and achieving that is mission impossible.”

A low turnout could unleash a scenario where the Zaev government is unable to persuade Skopje’s 120-member parliament to endorse the constitutional changes to push the name deal through.

Shilegov, a senior figure in the ruling social democrat party, is leaving nothing to chance. In recent weeks he has been going door-to-door to convince citizens of the need to cast ballots. “People have to have an opinion about this. They just can’t stay at home and go along with the boycott.”

But there are worrying signs. In recent months Moscow has intensified its campaign to spoil the vote, with the fiercely pro-Russia United Macedonia party leading the boycott drive. With its augmented staff, Skopje’s Russian embassy has been described as a hothouse of intelligence activity.

Visiting the capital, Mattis warned of the perils that lay ahead, accusing the Kremlin of employing underhand means and “malicious cyber activity” to scupper the vote. While Moscow has denied the charges, it has been open in its disgruntlement over Nato’s encroachment into the western Balkans, an area long regarded as a traditional sphere of influence.

“Skopje right now is a bit like Casablanca before the war,” said Trostanovski. “It is a city full of spies and operatives all watching how the vote will go.”