At a protest this month in Budapest against Prime Minister Viktor Orban, a man holds a toilet seat that reads “The system is crap.” (Darko Vojinovic/Associated Press/AP)

Charles Gati is a senior research professor of European and Eurasian Studies at the Johns Hopkins School of Advanced International Studies and the author of “Failed Illusions: Moscow, Washington, Budapest and the 1956 Hungarian Revolt.”

There is a new verb in Hungarian these days. “To Soros” — sorosozni — is to blame George Soros, the Hungarian-born American financier and philanthropist, for that country’s problems. He is accused of having bought off the European Union so that the bureaucrats of Brussels would impose his globalist values on Hungarian society; of devising a plan to bring millions of dark-skinned Muslim migrants to Europe, mainly via Hungary, to deprive the continent of its white, Christian tradition; and of sponsoring foreign agents — nongovernmental organizations — to topple Prime Minister Viktor Orban’s legitimate Hungarian government.

Hundreds of mammoth posters of a grinning Soros are displayed throughout the country, with the words “Don’t let him have the last laugh” superimposed on them. For good measure, the larger-than-life size of his hooked nose evokes the familiar stereotype of a scheming Jew. As Paul Lendvai relates in this well-informed and up-to-date biography of Orban, the Hungarian government runs a relentless campaign against the Soros-founded Central European University (CEU), by far Hungary’s and probably the whole post-communist region’s best graduate school. If Orban wins the parliamentary elections on April 8, CEU will have to move at least some of its classes from Budapest to Vienna.

The demonization of Soros is effective: A recent poll indicates that parts of the electorate plan to vote against the Soros Party in the forthcoming elections. That there is no such party is apparently irrelevant. What matters is that the current campaign against Western values falls on fertile soil. Orban’s supporters believe that if it were not for foreign enemies conspiring against Hungary, the country would be doing much better. What else can explain that Hungary is among the five poorest members of the European Union? How come close to 500,000 Hungarians, about 5 percent of the country’s population, have left in recent years for Western Europe? The official answer is that Hungary, as so often in its history, is once again being victimized by a conspiracy, this time developed by Soros and the E.U.

In matters small and big, Orban used to be the opposite of what he has become. When I first met him in 1989 at Szazadveg — the publishing arm of Fidesz, now the country’s dominant, governing party — he was the editor of the Hungarian-language edition of one of my two books that Szazadveg would issue in 1990 and 1991. We spent a lot of time together. His prized possession in the office was a large Xerox machine, a gift Szazadveg received from the Soros Foundation. Now, some three decades later, Soros may well feel that his good deed has not gone unpunished.

“Orbán,” by Paul Lendvai (Oxford University Press/Oxford University Press)

In this comprehensive study, Lendvai offers a detailed account of when and how Orban changed his spots over the years. He shows that Orban was an anti-Soviet radical in the 1980s, a strong critic of Russia for two decades, before becoming Vladi­mir Putin’s advance man in the E.U. in the past 10 years or so. No longer the liberal advocating Hungary’s rapid integration into European and transatlantic institutions, he has become a right-wing nationalist ranting against the E.U., Hungary’s major financial benefactor. He favors Hungary for Hungarians, recently going so far as to call his country’s Romani (gypsy) citizens “internal migrants” — as if they were not Hungarians. For good reason, Stephen K. Bannon, his political soulmate, has called Orban a “hero” and “the most significant guy on the [European] scene.”

Correctly, Lendvai considers Orban a shrewd and talented political chameleon. When Orban noticed in the mid-1990s that there was little serious competition on the center-right of the political spectrum, he skillfully positioned his party there. Then, over several years, he moved further and further to the nationalist right in order to take votes from the far-right Jobbik party (which, ironically, is navigating to the center now, thus crossing paths with Orban’s Fidesz). When, in 2015, he built a wall on the country’s southern border to keep out Muslim refugees, his popularity rose from 43 to 48 percent.

As a tactician, as well as a gambler and an improviser, Orban’s antagonism toward authority is an important clue to his approach to politics. He rebelled against the communists in the 1980s and the post-communist democratic elite in the 1990s, and he now agitates relentlessly against the “globalists” in Brussels and Washington. As he likes to say, he fights for Hungary day and night. In a revealing interview posted on YouTube, Orban candidly described his stubborn conflicts with his father. He traced what he called his “schizophrenic tendencies” to his teenage years, when his dad whacked him with his belt and physically forced him to stay at home on some weekends — even though he was already 18 years old. At 54, Orban is still uncomfortable accepting anyone else’s authority.

This is why — for political and psychological reasons — he seems eager to create the legal foundation for a new constitution that would effectively turn today’s semi-authoritarian order into a fully authoritarian one. If he is reelected in April with the super-majority he craves, he could further curtail the judiciary’s independence, further modify electoral law to stifle his remaining opponents’ chances at the polls and further curb freedom of the press. It seems that Orban’s model is Miklos Horthy’s antediluvian regime in interwar Hungary, a soft dictatorship that defied the country’s real and imagined foreign enemies and initially appealed to Hungarian pride. But it left humiliation and destruction in its wake at the end of World War II. If history were to repeat itself, Hungary’s slide from Central Europe to the Balkans would only accelerate.

It is hard to say if present trends could be reversed in the years ahead. The opposition at home, made up of Social Democrats and liberals, is weak and divided. In Fidesz, the party he continues to dominate, Orban’s colleagues are awed by his political skills and popularity — even though they are also afraid of him. Among foreign critics, Washington upholds the values of unfettered elections and a free press, keeping hope alive for a democratic revival, but Orban’s rather secretive and well-paid U.S. lobbyists work hard on his behalf. Their goal is a White House invitation to the Hungarian leader for a state visit. Lendvai’s fair-minded book is a reminder that the lobbyists’ claims about Orban’s democratic credentials and his goodwill toward the United States are fake news.

Could the European Union make a difference? In the past few years E.U. officials have put Hungary (and Poland) on their agenda, warned about withholding the E.U.’s huge, $3 billion to $5 billion yearly subsidies to Hungary’s economy (from the E.U.’s “cohesion fund”), and even considered suspending Hungary’s voting rights — but they have shied away from taking any forceful measures. Worse yet, Brussels is beginning to believe that time is on Orban’s side. With nationalism and sovereignty on his banner, and with the support of new adherents in Poland and Italy, in Britain and Trump’s America, too, he is an effective fighter against the continent’s integration and its partnership with North America. As Lendvai makes it clear, he should be taken seriously.

Hungary's Strongman

By Paul Lendvai

Oxford. 273 pp. $29.95