Jan-Werner Müller, a professor of politics at Princeton University, described Mr Orban as an “anti-liberal” who campaigns against the EU while his country benefits financially from membership of the bloc.
Mr Orban is a member of the European People’s Party (EPP), the EU’s centre-right group which represents mostly Christian Democrats – the original architects of European integration in the 1950s.
Writing in the Financial Times, Prof Müller said: “Not only are the EPP now tolerating a far-right populist such as Mr Orban in their midst, they are also blind to the fact that the Hungarian leader is making a bid for European leadership that could destroy Christian Democracy, and the EU, from the inside.
Hungarian prime minister Viktor Orban
Hungarian PM Viktor Orban is accused of trying to destroy the EU from within
Mr Orban’s government systematically disregards the rules of the European club and the supposedly shared values of democracy
Professor Jan-Werner Müller
“Hungary receives large subsidies from Brussels, yet Mr Orban’s government systematically disregards the rules of the European club and the supposedly shared values of democracy.
“Most recently his government passed a law which, for purely political reasons, aims at closing the Central European University, a Budapest-based bastion of academic independence and free thought founded by the billionaire philanthropist George Soros. (Tens of thousands took to the streets of the Hungarian capital on Sunday to protest against the new law.)”
Prof Müller accuses Mr Orban of manoeuvring himself into a position where he benefits from the support of the far-right at home while maintaining important connections with Europe’s liberal-leaning leaders.
He said Mr Orban presents himself as a supporter of EU Council President Donald Tusk in Brussels at the same time as starting an anti-EU campaign with newspaper advertisements and billboards proclaiming “Let’s Stop Brussels!”
Get Quotes on Home Insurance
Anti-Orban protestors take the streets of Hungarian capital Budapest
Every household in the country will receive a leaflet with leading questions intended to ram home the message that the EU is planning to impose higher utility prices and “illegal immigrants” on Hungary.
Prof Müller said: “In his speech at the EPP congress in Malta last month, Mr Orban laid out his vision of a Europe in which “there is room for our Christian identity, our national pride.”
“Such attempts to start a pan-European Kulturkampf against a left that allegedly wants to destroy Europe by letting in as many Muslims as possible used to find an echo only on the far right.
Opponents say Viktor Orban plays one side off against the other
Powerful images as migrants protest in Hungary
Tue, April 4, 2017
Migrants protest outside Budapest's Keleti Railway Station after it was closed off by police to prevent people travelling on to western Europe
1 of 53
A migrant taunts Hungarian riot police as they fire tear gas and water cannon on the Serbian side of the border, near Roszke
“But this changed after Hungary put up a fence at the border with Serbia. In Germany, Chancellor Angela Merkel’s coalition partner, the Bavarian Christian Democratic party, keeps inviting Mr Orban to put pressure on Ms Merkel to abandon refugee-friendly policies.”
Prof Müller said he could not understand how Europe’s Christian Democrats could vocally criticise "the anti-democratic excesses" of Turkey’s Recep Tayyip Erdogan or Russia’s Vladimir Putin while tolerating "egregious violations of the rule of law by one of their own?"
He accused Mr Orban of “slowly but surely undermining the union from within”.