Madrid is preparing for a major rally on Sunday called by opposition parties PP and Ciudadanos to reject the Spanish government efforts to dialogue with Catalan pro-independence parties. Several far right, neonazi and fascist groups such as VOX, España 2000, Hogar Social, Falange Española and Democracia Nacional have also called their followers to attend.

President Pedro Sánchez faces increased calls for resignation following an agreement with the Catalan government to have a non-partisan observer attend and coordinate meetings between political parties.

Pablo Casado, the opposition head and People’s Party (PP) leader, accused Sánchez of “high treason,” and said “his surrender to the independence movement” is the most serious felony” since a failed coup d’état in 1981. PP officials announced on Thursday that the party will pay for the traveling expenses of demonstrators living in other Spanish regions.

Ciutadans (Cs) leader Albert Rivera said that his party will table motions against Catalan-Spanish talks in all of Spain’s regional parliaments. According to Rivera, the only possibility for Sánchez to preserve his “honor” is to leave his post and call a snap election.