This essay investigates the reasons why Ferruccio Parri left the Italian Republican Party (PRI) to contribute to the creation of Unità popolare, the poll alliance of actionist roots uniting the Pri and Psdi left wings in conflict with their respective party. The genesis of UP. Stemmed from the debate on the electoral bill tabled by the De Gasperi Cabinet and passed by Parliament in March 1953. Dubbed "scam law" by the opposition, it aroused harsh contrasts on the characters of pluralistic democracy and the means apt to defend its integrity, in particular within the so-called "third force", the lay area fostering a political project alternative to the counter-position of blocs that had taken shape at geopolitical level. Anti-Communism and anti-Fascism polarized the confrontation. Though hostile to the existing proportional system, Parri feared the law in question would help the advent of a new Fascism under clerical guise, since it granted a substantial majority premium to the coalition which would gain the absolute majority of votes. In June 1953 polls, however, no force in the lists reached that threshold, and so UP won its battle and started off an original political experience that was to find in Parri its prominent figure.
Keywords: Ferruccio Parri, Unità popolare, Action Party, "scam law", "third force", anti- Fascism