Brussels - The leader of the European Parliament's dominant centre-right party has threatened to take a stand against Hungary if Prime Minister Viktor Orban does not respond to EU concerns over the erosion of democratic values in his country.

Rule of law proceedings against Hungary

The comments come ahead of the EU legislature's vote on whether to launch rule of law proceedings against Hungary.

The so-called Article 7 procedure, which has also been invoked against Poland, could ultimately lead to the removal of a country's voting rights in the European Union.

The vote of the centre-right European People's Party (EPP), to which Orban's Fidesz party belongs, will be crucial to achieving the required two-thirds majority to support the motion.

Values the European Union

EPP leader Manfred Weber - who last week announced that he wants to run for the post of European Commission president in next year's EU elections - said democracy, the rule of law and freedom of opinion are core values of the EPP and also the European Union.

"This is why I expect the Hungarian prime minister to approach the EU partners and show willingness to compromise," Weber said in an interview with German daily Bild.

"If that doesn't happen, we in the EPP have to say: 'Our values are not negotiable for us.' The Hungarian government is currently on a path that is worrying to many," the German EU lawmaker said.

The EU legislature is voting Wednesday on a damning report on Hungary, identifying a "systemic threat to democracy, the rule of law and fundamental rights." On Tuesday, Orban is due to participate in the parliament's debate on the report.