APRÉS had been founded in October 2018 by Emmanuel Maurel and Marie-Noëlle Lienemann after their departure from the Socialist Party and was close to La France Insoumise.

After splitting from the Socialist Party (PS), APRÉS formed a "new Popular Front" with La France Insoumise (LFI) to present a joint electoral list for the 2019 European Parliament elections.

During a party congress from 1 to 2 December 2018, 73.5% of members voted to create a "new political formation" with APRÉS in 2019 that would be the "home of the republican left.

"[6] The two parties merged on 3 February 2019 at a Founding Conference in Valence to establish the Republican and Socialist Left (GRS), with Maurel and former MRC spokesman Bastien Faudot as the first co-presidents.

The GRS's candidates on the list included Maurel, Catherine Coutard, Anthony Gratacos and Nouvelle-Aquitaine regional councillor Elisabeth Jutel.

The opening of the Universities was attended by several prominent left-wing figures, such as Arnaud Montebourg, Yannick Jadot, Fabien Roussel and François Ruffin.

[15] Political figures in attendance included LFI Member of the European Parliament (MEP) and co-president of The Left in the European Parliament Manon Aubry, essayist Jacques Rigaudiat, former secretary-general of the Syndicat de la Magistrature union Hélène Franco, former Greek foreign minister Georgios Katrougalos, Europe Ecology – The Greens MEP Marie Toussaint, secretary-general of the LFI delegation to the European Parliament Marina Mesure and Génération.s candidate in Provence-Alpes-Côte d'Azur Capucine Edou.