Wałęsa, who rose to prominence as the legendary leader of the Solidarity trade union movement, told a packed convention of over 1,000 Libertas campaigners on May Day that "Declan Ganley and Libertas have the potential to change Europe for the better".
The former Polish president urged voters to "heed the Libertas message" and put citizens back at the heart of the European project.
Wałęsa's speech provoked a lengthy debate in the Polish media, coming only a day after he had made a similar high-profile appearance at the campaign launch of the centre-right European People's Party (EPP) in Warsaw.
Wałęsa later told the press that he did not support Libertas or Declan Ganley, but rather went to Rome "to speak about new solutions which could best serve Europe". He also told Polish radio that he had been paid a considerable amount of money to speak.
Wałęsa claimed that while his first allegiance in this June's European elections was with the ruling Polish Civic Platform Party (PO, a member of the EPP), he would also like some Libertas candidates to enter the European Parliament: "It's better when radicals follow some rules," he said.
Explaining why he saw fit to appear at both conventions, he argued that he was "prepared to go anywhere people are talking about Europe," adding: "I won't listen to anybody who tells me where I should go and what I should say."
Wałęsa's son Jarosław (33), currently a PO member of parliament, will appear on the PO (EPP) list in Gdańsk for the European elections.
Libertas aims to win 100 seats in June
Meanwhile, the Libertas campaign launch in Rome confirmed that the party would run candidates in at least 23 EU countries.
Claiming to have "millions of names" on their party email list and "the most visited political party website in Europe," Declan Ganley told journalists that Libertas would present more than 200 candidates for the elections.
The Libertas leader claimed that if voter turnout were to increase by eight to 15%, his party's goal would be to win 100 seats. "The establishment is terrified of Libertas," he said.
With additional reporting from EurActiv Poland .
