BUDAPEST (Reuters) - Hungary’s Prime Minister Viktor Orban was due to hold crunch talks on Tuesday with the head of the European Parliament’s main conservative group which has threatened to expel his party over his anti-EU and anti-immigrant election campaigning.

FILE PHOTO: Hungarian Prime Minister Viktor Orban delivers his annual state of the nation speech in Budapest, Hungary, February 10, 2019. Banner reads "Hungary first!" REUTERS/Bernadett Szabo/File Photo

It will be their first face-to-face meeting since Manfred Weber, a German conservative who leads the European People’s Party (EPP) grouping, last week demanded Orban’s nationalist Fidesz Party apologize for its rhetoric.

Orban and his party have so far not apologized or made two other concessions demanded by Weber - widening a political rift in the EU’s biggest political bloc in the build-up to European Parliament elections in May.

There was no immediate comment from either side. But German Chancellor Angela Merkel, whose Christian Democrats are the biggest party in the EPP grouping, said Weber would reach a decision based on the outcome of the talks.

“People’s parties always have different political wings. But there are limits to the basis of values,” she told reporters.

Hungary’s government triggered the dispute with election billboards accusing European Commission president Jean-Claude Juncker and Hungarian-born U.S. billionaire George Soros of plotting to destroy European civilization through immigration.

Weber, the EPP’s candidate to succeed Juncker, has cast the issue of Orban’s rhetoric as a question of fundamental values ahead of the vote.

Hungary benefits from its influence inside the group. But Orban, who cultivates his image at home as a maverick who defies Brussels, has said Fidesz might have to leave the EPP and seek an alternative alliance.

Orban warned last week that the EU might break up if one part of it forced other parts to accept pro-immigration policies.

“WAITING FOR A SIGNAL”

Weber has demanded an apology to EPP member parties, an immediate and permanent end to Orban’s anti-EU campaigns and renewed government support for the Soros-founded Central European University to stay in Budapest.

Paul Ziemiak, party secretary of Merkel’s Christian Democrats, said it was prepared for all options.

“Weber mentioned the points which are important for him – that Orban has to acknowledge the values of the EPP. We are waiting for a signal from Budapest, if they (Fidesz) share these values or not.”

Orban and Weber will meet in Budapest, Orban’s press chief Bertalan Havasi was quoted as saying by state news agency MTI on Monday.

Hungary has said the billboards will be replaced this week with others touting Orban’s plan to lift the birth rate, though the old ones were still in place in the capital on Monday.

The Central European University said in December it had been forced out of Hungary after a years-long struggle between Soros, who promotes liberal causes through his charities, and the nationalist, anti-immigrant government of Orban.

The university said on Monday its expulsion was still in place.