In this role he took part in the great workers' struggles of the time, including that of the Fiat workers which ended with a 35-day occupation of the car manufacturer's factory. A committed and hardline trade unionist, Bertinotti affirmed the need for the working class to strike against the "injustices of the boss class", thereby attracting the anger of more moderate trade unionists. At that time he first disagreed with Sergio Cofferati, beginning a polemic which has continued, albeit in different forms, until the present.