Spain's Prime Minister Mariano Rajoy was to visit his Greek opposite number Antonis Samaras on Tuesday, an official said, in a show of solidarity between the two conservative leaders who are under siege by left-wing protest parties.
Meanwhile Podemos, a surprise contender in Spain's own vote due later in the year, voiced support for Syriza, the radical left-wing Greek party which is tipped to win the snap election on January 25th.
A Spanish government source said Rajoy was to travel to Athens for a working meeting with Samaras followed by a joint press conference and would return to Spain on Wednesday.
The source said Rajoy and Samaras agreed on the visit when they met on Sunday in Paris at the mass demonstration against last week's attack at satirical magazine Charlie Hebdo.
Spanish media said Rajoy would publicly back Samaras, who was forced to call the election following the dissolution of parliament after an inconclusive presidential vote in December.
Podemos threw its weight behind Alexis Tsipras, leader of Syriza, which like the Spanish party has fiercely criticized the austerity policies imposed in the aftermath of the economic crisis.
Syriza and Podemos have accused mainstream parties in their countries of bowing to other leaders such as Germany's Angela Merkel in imposing deep cuts.
Syriza's anti-austerity message has made it a serious challenger to Samaras's New Democracy and the Greek socialist party Pasok.
"There are two options in the new elections in Greece... the candidate whose name is Angela Merkel and who is represented by parties like Pasok and New Democracy, and the Greek candidate, and his name is Alexis Tsipras," Podemos head Pablo Iglesias said in a video posted Monday on YouTube.
"I am sure the Greek people are going to choose a Greek new president for the country," he added, speaking in English.
Tsipras appeared in public with Iglesias when the Spaniard was elected party leader in November.
Formally founded just a year ago, Podemos has overtaken Rajoy's conservatives and the mainstream opposition Socialists in several opinion polls.