Both the Socialists (PSOE) and the United Left grouping (IU) have called on Prime Minister Mariano Rajoy to resign if he is unable to tell the truth about his party's finances.
Following the publication of new revelations by former Popular Party (PP) treasurer Luis Bárcenas about the party's financing over the weekend, PSOE deputy secretary-general Elena Valenciano said all the signs indicated that the PP has been "mixed up in an illegal funding scheme" for the past 20 years. Furthermore, the "cleanliness of elections" was in doubt, she said.
Valenciano called on Rajoy to appear before Congress to provide explanations. "If Rajoy cannot tell the truth, he will have to go," she said after an extraordinary meeting of the PSOE's permanent executive committee to discuss the situation on Tuesday.
"The honor not of Mariano Rajoy, but of the prime minister of the government of Spain, is under question."
At the same time IU general coordinator Cayo Lara noted that if Bárcenas was telling the truth, the prime minister would have to resign and call new elections.
In an interview published by El Mundo newspaper on Sunday, but conducted before he was remanded in custody nearly two weeks ago, Bárcenas revealed that the PP had been illegally financing itself for at least 20 years, receiving cash donations from construction firms and other businesses in exchange for contracts from PP-run administrations.
It was the first time he had publicly confirmed revelations, first published in EL PAÍS, that he ran a parallel accounting system for the party while treasurer.