Nick covers Italy, the Vatican, Greece and the Balkans. He has reported for the paper since 2000, having previously covered Australia, New Zealand and the South Pacific 8:00am GMT Aleksandar Vučić has been Vladimir Putin’s last reliable friend in Europe.

But the Serbian president now faces the prospect of being swept away by a popular revolt after more than a decade in power as his country goes to the polls in its most important election for a generation.

It pitches the once seemingly invincible president against an upstart student movement that grew out of anger about the collapse of a railway station roof two years ago that killed 16 people.

Not since 2000, when Slobodan Milošević was overthrown, has there been such a consequential vote for this key Balkan power.

If Mr Vučić loses on Sunday, there will be profound geopolitical consequences, not just for the region but for Russia. And there could be violence on the streets if his supporters choose to vent their anger and disappointment.

Serbia under its president Aleksandar Vučić has been Russia’s closest European ally outside the former Soviet Union since the fall of Hungary’s Viktor Orbán Moscow fears a repeat of what happened in April in Hungary, when its longtime ally Viktor Orbán was toppled after 16 years at the helm of a pro-Russian, increasingly authoritarian regime.

Under Hungary’s new government, Russian diplomats have been expelled on national security grounds and a process of “de-Orbánisation” is now under way.

The loss of Mr Vučić after his 12 years in power, first as prime minister and then as president, would be another blow to the Putin regime.

Serbia is an important country for Russia – there are deep-rooted cultural and religious ties – and Moscow wields extensive soft power through RT Balkan, a branch of the broadcaster Russia Today, as well as through the Russian House, a cultural institute.

“The Russians would of course prefer to have Vučić remain,” Denis Cenusa, an expert on Russia and the Balkans, told The Telegraph.

“Vučić has been tested over time and through various crises. When there were wildfires in Serbia this summer, for instance, he turned to Russia first, and only called for assistance from the EU.

“Everything would change dramatically if Vučić loses – Russia will be left with just the Republika Srpska [the miniscule Serb-dominated part of Bosnia-Herzegovina] as its main focus in the Balkans. But that would leave them with just a tiny fraction of the influence that they currently have through Serbia.”

Student List candidate Ilija Srdanovic at an anti-government rally Dr Helena Ivanov, an expert on Serbia and the Balkans at the Henry Jackson Society think tank, added: “This is the most important election since 2000 and by far the biggest challenge that Vučić has faced since he came to power.”Moscow has been doing all in its power to prop up Mr Vučić and ensure that he wins the election.

It has deployed two main tactics: misinformation and scaremongering about the consequences of a defeat for Mr Vučić; and exercising leverage through the cheap energy that it supplies to Belgrade.

Russia recently renewed a contract with Serbia for the supply of natural gas at a third of the price available on the open market – but only until the end of the year.

The president retains deep pockets of support among Serbians attracted by his nationalistic rhetoric and alarmed at the prospect of losing access to cheap Russian gas“The message is ‘we’re waiting to see how you vote’,” said Mr Cenusa, a strategic analyst with the Geopolitical Security Study Centre in Lithuania.

“Russia sells gas to Serbia at a cost of €318 (£266) per thousand cubic metres, compared to European market prices of €1,000 per thousand cubic metres.”For ordinary Serbians who, like most Europeans, are struggling with the cost of living, it is not necessary to be militantly pro-Russia or pro-Vučić to appreciate the benefits of the deal.

Mr Vučić, who cannot be elected president again but hopes to be elected prime minister, will face off against the so-called Student List, the amorphous protest movement that grew out of a railway canopy disaster in the city of Novi Sad in 2024.

The Student List’s 250 candidates in the election include teachers, university professors, farmers, artists, a cardiologist and a rapper.

Moscow has characterised the Student List as a stooge of the West, comparing it to the “colour revolutions” that brought down various authoritarian regimes in the past, from the Rose Revolution in Georgia in 2003 to the Orange Revolution in Ukraine in 2004-05 and the Tulip Revolution in Kyrgyzstan in 2005.

The insurgent opposition has been reticent about their foreign policy position in a country with deep ties to Russia In June, Sergei Shoigu, the secretary of Russia’s Security Council, likened the youth movement in Serbia to the 2014 Maidan Revolution in Ukraine, which brought down the country’s pro-Moscow president.

A year ago, Russia’s Foreign Intelligence Service accused the EU of financing non-governmental organisations (NGOs) and media outlets in Belgrade to try to foment a “Serbian Maidan”.

“Moscow pushes the narrative that behind all these movements, including the one in Serbia, there is Western interference,” said Mr Cenusa, whose research expertise includes hybrid warfare and Russia’s influence in Europe and the Caucasus.

“They have alleged, for instance, that the Student List has received money from the West, especially Germany.”The Russians have also been at pains to remind the Serbs of their solidarity in the past: their condemnation of Nato’s bombing of Serbia in 1999 during the breakup of Yugoslavia, for instance, and their support for Serbia’s claims to Kosovo.

The president has been dogged by mass protests since corruption was blamed for the collapse of a railway station roof that killed 16 people two years ago One problem for Moscow, as well as for the EU, the US, and Serbia’s other main interlocutors, is that nobody knows how Serbia’s foreign relations would change if the Student List won the election.

The campaign has been fought almost exclusively on domestic policies, with the Student List vowing to clean up corruption, restore press freedom and return Serbia to fully functioning democracy.

“A (student-led) government would pursue broad reforms to tackle corruption, overhaul key public institutions and companies, and dismantle patronage networks,” the political risk consultancy Teneo said in an analyst note this week. “However, strong bureaucratic resistance could generate short-term institutional instability.”Moscow may take some comfort from one of the few foreign policy agendas that the Student List has committed to. It is opposed to imposing sanctions on Russia for its invasion of Ukraine.

There is deep uncertainty over who will win Sunday’s election. Polls in Serbia are not considered to be very fair or reliable, but they show the student movement holding very narrow leads over Mr Vučić’s Serbian Progressive Party.

“I am sure we will win, and I am sure that on the 26th (Monday) we will wake up in a free Serbia,” said student activist Masa Perepeliuc, a 21-year-old political science student in Belgrade.

To outsiders, the allegations of corruption and repression under Mr Vučić’s rule would seem enough to warrant the toppling of the Balkan strongman. But after 12 years in power, he is a consummate political operator. It would be naïve to write him off. And even if he is beaten, he may not concede defeat.

“For the first time in 14 years [the length of time that the Serbian Progressive Party has been in power], when people ask me who is going to win, I genuinely cannot give an answer,” said Dr Ivanov.