Discussions about Europe’s future have largely concentrated on Brexit in recent months, but some European politicians fear an even bigger threat to harmony on the continent is waiting around the corner, embodied by Hungary’s prime minister, Viktor Orbán.

Orbán’s Fidesz party has a two-thirds majority in the Hungarian parliament, which gives him leeway to make sweeping constitutional changes, and he has spoken of a plan to reshape the country over the next decade. He has installed loyalists in previously independent institutions, put a vast media network under the control of cronies and brushed off protests from the disgruntled urban elites.

But as EU nations, perhaps minus Britain, prepare for elections in May that could reshape the continent’s politics, Orbán is eyeing a bigger role than that of domestic strongman. This week could be a key turning point for the Hungarian leader, as the European People’s party, the centre-right grouping in the European parliament to which Fidesz belongs, mulls whether to kick out its most divisive member.

For nationalists across Europe, Orbán is a hero, the embodiment of a nativist leader willing to eschew liberal political correctness and speak aggressively about the need to defend so-called Christian Europe. Steve Bannon has called him Trump before Trump, and Nigel Farage and Italy’s Matteo Salvini are admirers.

For many liberals, and increasingly for some of his supposed allies in the EPP, he signifies all that is rotten, corrupt and downright scary in contemporary politics on the continent.

“The age of liberal democracy is at an end,” Orbán told the Hungarian parliament shortly after Fidesz won a third successive electoral victory last year. “It is no longer able to protect people’s dignity, provide freedom, guarantee physical security or maintain Christian culture.”

Viktor Orbán with Italy’s interior minister, Matteo Salvini. Photograph: Massimo Pinca/Reuters

His messaging, repeated in speeches and interviews ad nauseam, is that he is on a mission to protect Hungary and the rest of Europe from the evils of migration from the Middle East and Africa.

“Everything that serves to stop migration is good, and everything that encourages migration is bad,” he said recently, a succinct summary of his political rhetoric over the past few years, backed by a media that has put out a steady diet of scare stories about a decaying western Europe under siege. He has frequently accused the Hungarian-born financier George Soros of a conspiracy to overrun Europe with Muslim migrants.

One thing Orbán’s admirers and detractors agree on is that he has become symbolic of something bigger than the fate of a smallish central European state with a population of fewer than 10 million. The man himself clearly relishes his increasingly large role in European political discourse.

“Orbán’s self-image is that he is the big prime minister of a small country who earns the ire of the small leaders of bigger countries because he dares to speak the truth,” said András Vágvölgyi, a writer who knew Orbán in the late 1980s when today’s far-right nationalist was a charismatic proponent of democratic change. Even then, Orbán’s “ill-concealed egoism and power mania” led him to be nicknamed Little Nero, he said.

Guy Verhofstadt, the former prime minister of Belgium who leads the Alliance of Liberals and Democrats for Europe in the European parliament, has been involved in a bitter and long-running public mudslinging with Orbán. It culminated in the Hungarian government funding a truck to drive around Brussels plastered with a billboard featuring a montage of Verhofstadt’s face and images of terrorist attacks, and a banner calling him insane for claiming Europe does not have a migration crisis.

The Orbán government’s more recent poster campaign against the European commission president, Jean-Claude Juncker, led to renewed calls for the EPP to throw him out. The group’s president, Manfred Weber, is the EPP’s candidate for the next president of the European commission and has advocated keeping Orbán and his MEPs inside the EPP tent, but has recently shown signs of nearing breaking point. He visited Budapest last week and said the problems were not yet solved.

The expulsion of Fidesz is on the agenda for an EPP meeting due to be held on Wednesday in Brussels. Last week, in an attempt to mollify his critics, Orbán fired off a series of half-hearted apology letters to critics within the EPP whom he had previously termed “useful idiots”, leaving many of them unimpressed. “At this point, letters will not help. Fidesz should show its commitment to the EPP by its actions. This hasn’t happened,” tweeted Petteri Orpo of Finland’s Kokoomus party.

Brussels accused Budapest of peddling a ‘ludicrous conspiracy theory’ with its Jean-Claude Juncker poster. Photograph: Attila Kisbenedek/AFP/Getty Images

Frustrated with Brussels and other European critics, Orbán has built alliances with neighbouring countries, notably throughout the V4, which comprises Hungary, Poland, the Czech Republic and Slovakia, all of whose leaders have at times expressed varying degrees of unhappiness with the EU, and whose unity in messaging is growing. “I think the V4 could well become the strongest grouping in Europe,” said György Schöpflin, a Fidesz MEP.

The most frequent comparison is made between Orbán and Jarosław Kaczyński, the co-founder of Poland’s Law and Justice party, which has also attracted criticism from Brussels over rule of law concerns.

Poland’s prime minister, Mateusz Morawiecki, was in Budapest last Friday for Orbán’s keynote speech on Hungary’s national holiday. If the EPP does expel Fidesz, Orbán could seek to join Law and Justice as well as other nationalists in a newly configured European parliament.

Given the growing support for nationalist parties in western Europe, it would be simplistic to portray a new European divide between east and west, but it is undeniable that a new wave of nationalist “strongmen” leaders in the eastern half of the continent have drawn on Orbán’s example of channelling discontent against Brussels while concentrating power.

Orbán is the most outspoken of all the regional leaders and has presented the battle for the future of Europe in zero-sum terms, claiming the goal in the May elections is to ensure control of all European institutions is wrested from “pro-migration forces”.

For Orbán, the idea that he is up against an exhausted, decaying vision of Europe is one that he has returned to again and again in his speeches. Last October, he implicitly compared today’s EU to the Nazis, Soviets and other imperial powers.

In his speech on Friday, he was unusually muted on Brussels and Soros, perhaps keen not to provoke his EPP critics further on the eve of their decision. However, he used the visit of Morawiecki to warn that central European illiberals will stick together.

“We are preparing for a central European renaissance of overwhelming power,” said Orbán on Friday. “When Poland is attacked from Brussels, the attack is against the whole of central Europe, and against us Hungarians. To empire builders who seek to cast their shadow over central Europe, we have this to say: they will always need to reckon with the strong bonds between Poland and Hungary.”

Verhofstadt has accused Orbán of using anti-migration rhetoric as a cynical smokescreen for corruption and cronyism, and agrees that the May elections will be important in determining the future vision of Europe.

“Can the European Union remain a bastion of freedom, liberal democracy, hope, tolerance and fundamental rights, or do we become more authoritarian, more corrupt, with fewer rights?” asked Verhofstadt. “The rise of ‘mini-Trumps’ in central and eastern Europe is more of an existential threat than Brexit. We now face a battle for Europe’s soul.”