WARSAW, Poland -- Italian Interior Minister Matteo Salvini is visiting Warsaw on Wednesday to meet with Poland's powerful ruling party leader as well as his Polish counterpart, as their populist-nationalist parties explore a possible alliance in spring elections for the European Parliament.

The May elections are shaping up into a battle between liberal pro-European Union forces, among them French President Emmanuel Macron, and populist euroskeptics represented by Salvini and several other populist politicians.

Salvini's planned meeting with Polish ruling party leader Jaroslaw Kaczynski is being watched as an early sign of whether the Italian firebrand can effectively mount a nationalist challenge at the European level.

Salvini is also meeting with Joachim Brudzinski, the interior minister, but the meeting with Kaczynski is being watched with greater interest given Kaczynski's role as the country's de facto leader, the official understood to be the real power behind the government despite his lack of any formal government portfolio.

Salvini's League, which is one of two parties in Italy's ruling coalition, and Kaczynski's Law and Justice party, which governs alone, are both staunchly anti-migrant and criticize how the EU functions today.

However, Polish skepticism of Salvini's friendly approach to Russian President Vladimir Putin could be an impediment to collaboration.

Both populist governments have been embroiled in conflicts with Brussels that have seen them strive for greater national sovereignty. Poland's clash has involved changes to the judicial system seen as anti-democratic, while Italy's has centred on its budget spending.

Before Salvini's visit to Warsaw, Polish ruling officials sounded positive about possible co-operation. Polish Deputy Foreign Minister Konrad Szymanski called Italy's government the "forerunner of change" in Europe.

Jacek Czaputowicz, the foreign minister, recently said the Salvini-Kaczynski encounter would be "a meeting at the highest level" and said it would involve discussions about the elections to the European Parliament.

"If chairman Jaroslaw Kaczynski admits a politician, this also testifies to a special relationship," Czaputowicz said.

The ruling party is facing sharp rebuke by its domestic critics for its apparent openness to working with Salvini.

Poland's main opposition leader, Grzegorz Schetyna, on Wednesday called the meeting between Salvini and Kaczynski "absurd and shocking," referring to Salvini's League as a "nationalist, radical and pro-Russian party."