The slogan of the rally, which will be attended by the representatives of 11 right-wing European parties, is "Italy first! Toward a Common Sense Europe."
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Marine Le Pen, the leader of the French National Rally, is also expected to join the rally.
Salvini is seeking to build a pan-European bloc of populists ahead of the elections to the European Parliament, in which his party is projected to gain as many as 26 seats.
Apart from Lega, Salvini's alliance also includes the Alternative for Germany, The Finns Party, the Danish People's Party, the French National Rally party, Austria's Freedom Party and the Conservative People's Party of Estonia.