In 1935, he impelled a merging with the party Esquerra Valenciana (Valencian Left, EV), founded in 1934 and led by Vicent Marco Miranda (ex-Mayor of Valencia), Josep Benedito, Miquel Duran de València and Manuel Sanchís-Guarner.

After Vicent Marco obtained in 1936 the act of deputy in Valencia within the candidatures of the Popular Front both parties joint in a common parliamentary group in the Spanish Congress with the name of Catalan Left.

The Spanish Civil War truncated many political projects in which Esquerra Valenciana participated, the most important of which was a project of a Valencian statute of autonomy with the official name of País Valencià (rendered in English by some as "Valencian Country", see names of the Valencian Community), which would have granted similar autonomous powers as with the other so-called historical nationalities in Spain (namely, Andalusia, Basque country, Catalonia and Galicia).

In spite of it, Esquerra Valenciana, the main party in which ERPV had diluted, reached their maximum growth in that period, arriving to exceed 10,000 affiliated.

Then, at the following 2008 Spanish general election, which saw ERC's results halved in Catalonia, Agustí Cerdà was one of the incumbents who lost his seat.