I can speak for Italy. Short answer: they were neither repressed, nor co-opted, nor unpopular. The electoral results and parliamentary dynamics were simply such as to always keep them out of the national government, even if they managed to administer various regions and cities.

First, the partisans (half communists, a quarter left-wing other forces, a quarter right-wing) did not liberate Italy by themselves. The Allied armies rising from the south made the main part, even if the Italian partisans gave enormous help in terms of information, sabotage and attacks on the rear lines of the Axis, keeping one third of the German divisions busy away from the front and the totality of the Italian collaborationist army (Kesserling, the Axis commander in the Italian theater, affirms this in his autobiography "Soldier until the last day"). In the West they were undoubtedly the most active and effective anti-German guerrilla.

Unlike in Yugoslavia, when the war ends in Northern Italy it is true that there are many armed communist militants, but also there is an equivalent number of equally armed non-communist militants and above all the American troops in war gear who were garrisoning the defeated country. This disparity of forces and the example of the civil war in Greece, where Stalin left the local communists alone so as not to interfere with the Anglo-American "sphere of influence", advised against following the revolutionary path to power. Added to this is the "turning point of Salerno", when in 1944 the leader of the Italian Communists Palmiro Togliatti agreed with the Italian government (led at the time by General Badoglio) and the other anti-fascist parties to join a government of national unity and postpone both the debate on the monarchy and the constitutional reform until the war is over. Therefore the Italian communists were in government together with the other political forces from April 1944 until June 1947.

On April 18, 1948 there were the most important elections in the history of the Italian Republic. The year before, the Italian Communist Party (PCI) had left the government, following the breakdown of relations between the United States (to which the government of Alcide de Gasperi was close) and the Soviet Union (to which the PCI remained faithful) . In these elections the pro-American bloc headed by the Christian Democrats (DC) and the pro-Soviet bloc headed by the PCI faced each other. The affirmation of the DC was clear and the defeated PCI was forced into opposition. While the Communists will remain Italy's second largest party, accounting for around 30% of the vote for the next 44 years, they will never be able to overtake the DC in elections and will never be able to form an alternative governing coalition. The moment in which he came closest to the government was the late seventies, in which the dialogue between DC and PCI became intense and a "grand coalition" government seemed imminent. But everything was stopped by the assassination of the politician Aldo Moro in 1978, the main proponent of this dialogue.