The EPP’s Manfred Weber, Socialist candidate Frans Timmermans, ALDE’s Guy Verhofstadt and the Greens’ Ska Keller will participate in a debate in Florence.
The debate, co-organised by the European University Institute, is the latest in a series organised to help the candidates flag up their policies and spell out their plans for the future of the EU.
Each of the politicians are also due to appear in a debate that will be televised by EBS on 15 May in Parliament, the last before the elections.
Weber, a German MEP, and Commission Vice President Timmermans, who already debated in French earlier this month, will face each other again on May 16 on German ZDF and Austrian ORF.
Weber was a notable absentee from yet another debate last week in the Dutch city of Maastricht, citing “other commitments”.
The elections mark the start of a new political cycle in the EU with a changeover of top jobs at the European Commission, Council and European Central Bank.
Tonight’s debate in Italy is one of three such events with the lead candidates from the main parties. It will be broadcast live from 6pm CET.
Czech ECR MEP Jan Zahradil, another lead candidate, is not taking part in the Florence debate but will answer questions in a Facebook live interview this afternoon, starting at 3pm.
"Current polls suggest the centre-right European Peoples' Party (EPP) and centre-left Socialists & Democrats (S&D) are likely to remain the largest groups in Parliament, but are likely to lose their combined majority for the first time"
A spokesman for the “State of the Union” debate in Florence, organised by the Financial Times, said it will have a special emphasis on “21st-century democracy” in Europe, a theme “of particular relevance” in the run-up to the European elections at the end of May.
The four Commission presidency lead candidates, or Spitzenkandidaten, are competing to replace Jean-Claude Juncker as President of the European Commission.
With the election due to take place on 23-26 May, current polls suggest the centre-right European Peoples' Party (EPP) and centre-left Socialists & Democrats (S&D) are likely to remain the largest groups in Parliament, but are likely to lose their combined majority for the first time.
Eurosceptic and anti-immigration parties, currently divided between the Europe of Nations and Freedom (ENF) and Europe of Freedom and Direct Democracy (EFDD) groups, look set to make the greatest gains.
Some of these parties intend to form a new group, with the possible name the European Alliance of Peoples and Nations, after the election.
If Brexit has not occurred by May 22, the UK will participate in the election and Parliament's 751 seats will continue to be allocated as they were in the 2014-2019 parliamentary term.
When the UK leaves the bloc, the number of seats will shrink from 751 to 705, with 27 of the UK's 73 seats reallocated to other countries.