Enrico Berlinguer was a giant of the Italian left in the 1970s and 80s, coming close to leading the Communist party into government through a “historic compromise” with the country’s Christian Democrats, and championing “Eurocommunism”, a liberal, anti-Stalinist version of Marxism that briefly swept the continent.

But his death 40 years ago, and the collapse of Europe’s communist parties in the late 1980s, eclipsed Berlinguer’s legacy, and Italy has since moved across the political spectrum, electing the far-right Giorgia Meloni as prime minister in 2022.

Now Berlinguer is having a revival in popularity, including among rightwing figures, as a film about his life opens the Rome film festival next week before an international release.

Berlinguer – La Grande Ambizione (The Great Ambition) will take viewers through the historical events that marked his career, from challenging the dogma of the cold war, and narrowly escaping an attempt on his life in Bulgaria, to taking the Italian Communist party (PCI) to the brink of power in the 1970s and standing firm against the political terrorism that seethed in Italy during that period.

Andrea Segre, its 48-year-old director, described the biopic as “a journey through a piece of history that I did not live through and which I learned to understand”.

This quest for knowledge about Berlinguer – who died on 11 June 1984 aged 62, four days after suffering a stroke while delivering a campaign speech – also spurred thousands of young Italians to visit exhibitions about his life held this year in Rome and Bologna.

“Frankly, we didn’t think the exhibitions, and all the other initiatives we have been doing for the 40 years since his death, would attract so much attention, affection and esteem,” said Ugo Sposetti, a former PCI parliamentarian and president of the Enrico Berlinguer foundation. “There has been a swell of participation among young visitors. These people were around 25 or 26 years old, who perhaps only knew about him through family conversations.”

Berlinguer was born in Sardinia in 1922, a few months before the fascist dictator Benito Mussolini seized power. He joined the PCI in 1943 and was arrested a year later for taking part in a protest to demand essentials for the working class, such as bread and sugar. Elected leader in 1972, Berlinguer pursued a more moderate line for the PCI. Championing a democratic route to socialism, he distanced the party from the influence of the Soviet Union and pitched it as a proponent of national unity.

He was much loved at home – for his sincerity, humanity and for working in the interests of the country rather than for personal power. Internationally he was feared, by both the left and the right. During the 12 years he led the PCI, Berlinguer took the party to the peak of its success, reaching the so-called “historic compromise” with Aldo Moro, leader of the Christian Democrats and a five-time prime minister. The alliance pact was inspired by the overthrow of democracy in Chile in 1973, but never came to fruition as Moro was kidnapped and killed in 1978 by far-left terrorist group the Red Brigade, derailing the coalition government just as it was about to be formed.

Support for the PCI dwindled after Berlinguer’s death, but his legacy has endured. For today’s leftwing supporters, this can partly be explained by a yearning for a good-quality, non-divisive leader with long-term vision.

More intriguingly, Berlinguer is also admired by the right. Meloni, whose Brothers of Italy party has neofascist roots, caused a stir when she paid an impromptu visit to the Berlinguer exhibition in Rome one evening. After being given a tour by Sposetti and avidly listening to some of Berlinguer’s most powerful speeches, she left a message in the visitor book noting that his life had been a “political story” and that “politics is the only possible solution to problems”. Critics balked, with some ex-PCI members expressing relief that they had not bumped into her. But given that Giorgio Almirante – the founder of the neofascist Italian social movement, whose youth wing Meloni joined in the early 1990s – has paid his respects to his political adversary in the chapel of rest, her visit might not be so unusual.

“It was perhaps a surprise to the least attentive,” said Sposetti, adding that he had good relations with Meloni despite their differing views. “Meloni grew up on bread, water and politics. She has a vision of [political] parties, of militancy, similar to what I had … but naturally she believes one thing, and I believe another.”

Berlinguer was also praised by Ignazio La Russa – a Brothers of Italy co-founder who in 2018 was filmed showing off fascist memorabilia in his home – at a party convention during which La Russa was interviewed by journalist Bianca Berlinguer, the late communist leader’s daughter.

Sposetti said these public displays of admiration were perhaps “opportunistic”. But Mario Ajello, a journalist and political commentator for the newspaper Il Messaggero, believes it is because Berlinguer was recognised as being a “morally impeccable” leader capable of uniting opposing forces. “There is also some nostalgia today for the old parties and when they functioned well, and when Italy functioned,” he said. “Berlinguer was a guarantor, not only of his party’s interest, but for the general interest.”

He added: “As for the far right, they do it to show they have overcome ideological barriers – because if you were a great Italian, even if you were a communist, they can appreciate you.”

Meloni was also invited by Rome’s centre-left mayor, Roberto Gualtieri, to the opening ceremony of the Rome film festival on 16 October. “This is normal, and a correct institutional relationship should never be lacking,” he said, adding that despite their political differences, he has “a good personal relationship” with Meloni.

• Berlinguer: The Great Ambition is in Italian cinemas from 31 October and will later be released internationally.