Elections in Europe later this month to select lawmakers to represent the European Union's 28 member nations are likely to be dominated by controversial issues, including rising populism, difficult relations with the United States, and rampant migration. But, while the bloc's 400 million voters will be lobbied by fringe parties with radical, nationalist views on the key issues ahead of the May 23 to May 26 elections, fringe ideas and controversy was largely absent from a crucial TV debate on Wednesday evening that featured six major EU personalities.

The six who took part in the debate all want to replace outgoing European Commission President Jean-Claude Juncker, who leads the powerful executive that proposes new EU laws and which ensures the bloc's procedures are followed.

Their number did not include populist or far-right politicians but such candidates are predicted to do well in the vote to select MEPs for the 751-member European Union Parliament. Radical parties are expected to perform well throughout Europe, but especially well in the United Kingdom, France, and Italy.

Juncker, who is stepping down in November, says the EU would be plunged into chaos if the populists do well in the elections and are then pandered to by whoever replaces him. He warned the candidates not to "underestimate" nationalists and far-right candidates, and not to deal with them to win control of the European Parliament.

"I see this election as serene and calm, but deeply concerning, because I see the margins of the political spectrum questioning the European project," he said in an interview with Austrian newspaper Der Standard. "What happens to the next commission will depend on the way the next European Parliament is put together.

"The extreme-right is the greatest danger … If the forces of the extreme-right and extreme-left have too much influence in the European Parliament, then all the debates may not be fully dominated but strongly influenced."

But candidates taking part in the TV debate did not focus extensively on the threat to Europe from rising nationalism, focusing also on climate change, migration, trade, and economics.

Frans Timmermans, a socialist candidate and the European Commission's vice-president, suggested that the rise of the far-right means the time is ripe for a left-wing coalition featuring MEPs from the far-left, the Greens, and the Liberals.

"My offer is let's work together in the next five years so that we make sure that the next commission puts the climate crisis on the top of its agenda and I am sure we will convince many, many people in the liberal family so that we create an alliance going from (Greek Prime Minister Alexis) Tspiras to (French President Emmanuel) Macron," the Dutch politician said.

Manfred Weber from the European People's Party, who is favorite to succeed Juncker, said he wants to "open the next chapter" for the new EU executive, but, according to pundits, failed to stand out as the obvious next leader.

Voters in the UK will be among the 400 million eligible to take part in the elections, even though the nation is in the process of leaving the bloc. Many UK voters are thought to see the elections as unnecessary as a result and are predicted to be ready to use the opportunity to embarrass the Conservative Party government of Prime Minister Theresa May by voting for fringe candidates. The Brexit Party, led by anti-EU radical Nigel Farage, is forecast to do well as a result.

The six candidates seeking Juncker's job are Jan Zahradil from the European Conservatives and Reformists, Nico Cue from the European Left, Ska Keller from the European Green Party, Margrete Vestager from the Liberals, Frans Timmermans from the Party of European Socialists, and Manfred Weber from the European People's Party.