Acting Prime Minister Mariano Rajoy's party has seen graft case after graft case smear its image during its four years in power, at a time when many Spaniards suffered the effects of tough spending cuts sparked by an economic crisis.
Esperanza Aguirre, president of the PP in the Spanish capital region and a former education and culture minister under former prime minister Jose Maria Aznar, was questioned over alleged embezzlement by members of the Madrid chapter of the party.
"As far as I know, there is no illegal financing at the PP in Madrid," the 64-year-old, who was regional president for nine years, told local lawmakers.
Asked how she could have ignored the alleged illegal practices at her party, Aguirre responded that she had supervised annual budgets worth USD 19 billion and could not have known about the activities of every single member.
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This is but the latest case affecting the PP.
Acting Deputy Prime Minister Soraya Saenz de Santamaria was also forced to announce the resignation of one of her main associates in connection with a corruption scandal at a state-run water company he once oversaw.
And PP members are also due to be questioned by a judge over how exactly the hard-drives of former party treasurer Luis Barcenas, who is in jail for embezzlement, were wiped clean before investigators were able to see them.
Corruption was one of the issues that cost the PP votes in December elections, which the party won but without the absolute majority it got in 2011 polls.