Budapest argues its anti-migrant measures and its defence of sovereign rights are in tune with the mood of European voters, who will elect a new parliament in Strasbourg next May.

But Judith Sargentini, who is spearheading a vote Wednesday on whether to take action against Hungary, warned her fellow MEPs that the 28-nation bloc's founding values are at stake.

"Do you want the rule of law?" demanded Sargentini, a left-wing Green MEP from the Netherlands.

Her proposed resolution warns that Hungary's actions represent a "systemic threat" to the bloc's democratic founding values.

It voices concerns about the Hungarian judiciary's independence, corruption, freedom of expression, academic freedom, religious freedom, and the rights of minorities and refugees.

Opposition to Orban's vision does not just come from the left.

There is disquiet in the main centre right parliamentary group, the European People's Party (EPP), about his position, despite it including his Fidesz party.

"MEPs from the centre right have a clear choice next week," declared Guy Verhofstadt, head of the liberal ALDE group.

"Support freedom and EU values by sanctioning Orban, or capitulate to far right populists who promote unfreedom."

It would be the first time the European Parliament votes to take steps under article seven of European Union treaties, which could ultimately deny Hungary its EU voting rights.

But the European Commission, the EU's executive arm, launched similar steps under article seven against Poland in December last year over its alleged threat to the independence of the courts.

Poland's ally Hungary has pledged to veto any move to impose such penalties on Warsaw, which would effectively block the measure.

Nor is it clear whether Sargentini's preliminary procedure will win the necessary two-thirds support of the assembly.

While Orban's actions have provoked opposition, they have been applauded by populists elsewhere in the EU, with several prominent far-right figures floating the idea of a pan-European populist alliance ahead of 2019 elections for the bloc.

On Monday the leader of Austria's far-right party, Vice Chancellor Heinz-Christian Strache, said he would "gladly" invite Orban's party into a common bloc, and Italy's new far-right Interior Minister Matteo Salvini has also expressed admiration for Orban.