Opposed to Italy's entry into the Second World War (a stance dictated by his conviction that defeat was certain), he struggled to find work.

In 1943, Giannini also directed four feature films in a year, including Grattacieli and 4 ragazze sognano, both with Paolo Stoppa as the protagonist.

Tired of the fascist dictatorship and the intrusion of politics in the lives of private citizens, but also of the return of traditional parties, Giannini, following the success of the weekly newspaper, founded an opinion movement called Common Man's Front.

It received 5.3% of the votes in the parliamentary election of 1946, getting 30 deputies to the Constituent assembly, including Giannini himself, who became group leader in the Parliament.

In 1947, Giannini, after having tried an alliance with the Christian Democracy and the Italian Social Movement, approached the communist leader Palmiro Togliatti, whom two years before he had described as "worm, rogue and forger".