The main opposition Radical Left Coalition (SYRIZA) party has a great deal vested in Thursday’s speech by SYRIZA leader Alexis Tsipras at 7 p.m. at Omonia Square. Mr. Tsipras will deliver his pre-election message in the presence of Spanish Podemos (meaning “We Can”) General Secretary Pablo Iglesias and French Communist Party National Secretary Pierre Laurent.

The presence of Podemos in particular is noteworthy as the party is a force to be reckoned with in Spain. The party rose from the aftermath of the Indignados movement against inequality and corruption in 2011 and became the third largest party in Spain within the first 20 days it allowed membership.

A possible SYRIZA-Podemos alliance is proof that a European South may rise in reaction to the austerity measures imposed by Berlin’s government. The SYRIZA headquarters at Koumoundourou Street want to send a clear message of the party’s superiority at the gathering on Thursday.

Mr. Tsipras is expected to send an invitation to conservative voters as well as center-left and leftist voters so that the party can create a viable majority government.

The party’s pre-election campaign will conclude on Friday during the all-channel telecast of Mr. Tsipras’ interview at Zappeion Megaron in Athens and a meeting later at Herakleion, Crete.