If there is one thing on which Brussels insiders and Eurosceptics can agree, it’s that the EU has experienced a decade of crises. The eurozone crisis and the subsequent enforcement of fiscal austerity exposed the coercive underside of Brussels. The arrival of refugees in 2015 tested the limits of European liberalism. Brexit, the first time a member state has handed back its EU membership, wounded the self-image of the EU as an ever-expanding bloc. But as serious as these challenges are, none of them threatens to shake European integration like the entrenchment of the far right in two member-state governments.

Europe’s real tumult lies in the failure of its centre-right parties to avert the rise of the far right. In Hungary, the prime minister, Viktor Orbán, who is about to celebrate his 10th year in office, has developed a rule book for how to stealthily undermine democratic institutions and the rule of law while still appearing to follow legal procedures. For the last decade, his Fidesz party has had a large enough majority in parliament to change the constitution according to its autocratic whims. It has transformed the electoral system such that a real turnover in power is now virtually impossible. Last year, the widely respected democracy watchdog Freedom House downgraded Hungary’s status to a “partly free” country – the first time this has happened from within the EU.

Rather than cutting off their oxygen, the EU has perversely enabled autocratic politicians

It’s hardly as if Brussels didn’t notice. In 2010, when the Hungarian government took control of the country’s independent media regulator, EU commissioners sounded the alarm and requested amendments to the law. Orbán outsmarted them with cosmetic adjustments and deployed an argument that you still hear today: if the EU interfered too aggressively it would turn yet another member state into a bastion of Euroscepticism. The implicit message was clear: if Europe didn’t like Orbán, it might one day have to deal with a party even further to the right, such as the radical nationalist Hungarian party Jobbik (observers may have noticed that Orbán often copied the policies of Jobbik, for example by starting a xenophobic campaign against refugees).

Rather than cutting off their oxygen, the EU has perversely enabled autocratic politicians. The billions it pays out in infrastructure subsidies are the equivalent of petrodollars for oil-rich dictatorships – a free resource to distribute among cronies and buy popular support. Hungary’s richest man – seen by analysts as a straw man for Orbán – is a regular recipient of government contracts. A decade or so ago, he was a gas fitter in Orbán’s hometown; today, he’s worth €1.3bn.

To some Brussels insiders, inaction over Hungary seemed excusable. Hungary was probably just one bad apple in an otherwise flourishing orchard, a country whose domestic politics were of no particular concern to western European capitals. Others worried that Brussels shouldn’t appear to prescribe domestic political institutions after it had dictated member states’ budgets during the eurozone crisis. These both proved fatal conceits.

Soon enough, there was a second bad apple. Jarosław Kaczyński, current leader of Poland’s Law and Justice party (PiS), announced in 2011 that he wanted to create “Budapest in Warsaw”. One need not be a conspiracist to believe that at a meeting of the two politicians in 2016, Kaczyński was inspired by Orbán’s strategy for undermining the rule of law. Since the party came to power in 2015, PiS has captured Poland’s judiciary and enjoys direct control over the body that appoints judges. The country’s judicial arrangements, according to Freedom House, are “incompatible with the European Union’s democratic values”.

Once there were two rogue actors, sanctions against either of them became practically impossible. As members of the European council, Poland and Hungary could veto such measures. The EU was founded on the idea that member states could trust each other, particularly in the application of EU law. If the rule of law is destroyed in Polish and Hungarian courts, which are also EU courts, member states can no longer trust each other to apply EU law, or engage in what EU treaties describe as “sincere cooperation”.

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Although Hungary’s autocratic turn may not be visible to the casual observer or the tourist who arrives in Budapest, it threatens to undo the project of European integration. The bulk of responsibility for this predicament lies with the very parties that were instrumental in creating European integration in the first place: the centre-right Christian Democrats.

They have consistently shielded Orbán in the European council, where Fidesz belongs to the European People’s party (EPP) – the supranational family of Christian Democratic and centre-right parties in the European parliament. For the EPP, Orbán is a strategic ally who reliably delivers seats in the European parliament, allowing the affiliation to maintain its status as Europe’s largest group and therefore retain its claim to the post of European commission president.

This pattern is visible across Europe. Centre-right parties have been unable to deal with the rise of the far right. For mainstream conservatives, a default option has been to denounce far-right parties while parroting their policies. The Conservative party in the UK has adopted the Eurosceptic policies of Ukip, while Les Républicains in France have emulated Marine Le Pen’s programme and, increasingly, her rhetoric. Rather than contain the threat of the far right, Europe’s centre-right parties have pulled it into the mainstream.

The entrenchment of the far right in Poland and Hungary also casts doubt on one of the EU’s major achievements. Joining “Europe” was once viewed as a bulwark against the return of authoritarianism. Hungarians and Poles living under emboldened authoritarian governments are right to feel betrayed by Europe. We may find, in the end, that the crisis of the centre-right rots Europe from within.

• Jan-Werner Muller is professor of politics at Princeton University