Alecu Constantinescu continued to collaborate with some former PSDMR members who remained dedicated to the workers' cause, such as I. C. Frimu, Alexandru Ionescu, Ştefan Gheorghiu, and Mihail Gheorghiu Bujor. At the end 1902 he departed for Paris, France, however he kept contacts with Romanian workers' movement, occasionally sending articles for the socialist newspaper "1 Mai" ("May Day"). Returning to Romania in 1904, he worked along Frimu and Bujor towards the reorganisation of the Romanian trade unionism. In August 1906, the Conference of trade unions and socialist circles elected Constantinescu secretary of the General commission of the trade unions, the first Romanian general labour organisation. In the same period he joined the editorial board of "România Muncitoare", becoming its executive editor. The newspaper was the main socialist venue of the time, and helped organise several strikes. Alecu Constantinescu himself began in 1906 a tour of Romanian cities, helping organise the local workers, in the hope of creating an unified national trade union. In 1907, during the Romanian Peasants' Revolt he was in Paşcani, in Moldavia, one of the centres of the rebellion. Due to his activism among the local workers in support of the peasants he was imprisoned for lèse majesté, however the Fălticeni court cleared him of charges few weeks later.