Discussion over whether Prime Minister Viktor Orban's Fidesz party should remain part of the center-right European People's Party intensified after the Hungarian government launched a public ad campaign last month opposing the positions of EU leaders on migration.
Critics see anti-Semitic undertones in the billboards, posters, print and television ads that carry images of Hungarian-American billionaire George Soros and European Commission President Jean-Claude Juncker.
By suggesting that Soros influences European Union policies on mass migration, some of those offended by the campaign say it evokes Nazi-era propaganda that portrayed Jews as puppet-masters and international enemies.
Orban said in an interview with Germany's Welt newspaper that EU parliament members who want Fidesz kicked out of the European People's Party were "useful idiots" for the left, using an expression commonly attributed to Lenin.
"While they believe they're fighting in a spiritual struggle, in fact they're serving the power interests of others — indeed, of our opponents," Orban said.
Orban said Hungarians don't consider the posters anti-Semitic.
"I can't do anything about the fact that George Soros is a Hungarian of Jewish origin," he added. Soros has been the target of various Hungarian government smear campaigns in the past few years.
The European People's Party is the largest trans-national political group in the European Parliament. It was founded to represent Christian Democrats.
Some of Fidesz's fellow members, including parties from Belgium, Portugal, the Netherlands, Sweden, Finland, Luxembourg and Greece, have fiercely criticized Hungary's campaign. The ads follow years of grumbling within the group over Orban's efforts to build an "illiberal state."
The European Parliament voted in September to launch a sanctioning process over the Hungarian government's perceived shortcomings regarding the rule of law and European values. The procedure could lead to Hungary losing its voting rights in the EU.
In his interview with Welt, Orban seemed to offer a possible compromise, which on closer inspection hardly changed his position on the migration policy campaign.
He told the newspaper that government ads against Juncker would soon be withdrawn. However, he said Fidesz would be launching its own campaign, with European Commission Vice President Frans Timmermans replacing the EU chief.
Timmermans is the lead candidate of the Party of European Socialists to succeed Juncker after May's European Parliament election. He has been highly critical of Orban, and Orban has repeatedly expressed his disdain for the Dutch politician.
The European People's Party candidate seeking to succeed Juncker, Manfred Weber, tweeted in response to Orban's interview that the Hungarian leader was "following the wrong political path, particularly when it comes to style or fundamental questions about the democratic order."
Weber linked to his interview with Germany's Der Spiegel magazine, published Friday, in which he said "Orban badly damaged the EPP" with the Soros poster campaign.
In the interview, he said Orban had a "weak" approach that relies on "scaremongering" instead of persuasive advocacy.
"I expect him to apologize and put an end to the poster campaign," Weber said in the interview. "Beyond that, we cannot simply return to business as usual....We will take concrete steps very soon."
He did not say whether he'd support the removal of Fidesz from the EPP, but told Spiegel "all options are on the table."
"Enough is enough," Weber said. "That is our message."