Rita Barbera, a Popular Party (PP) senator who governed Valencia, Spain's third-largest city, for more than two decades, agreed to be questioned by a judge investigating alleged money laundering by the conservative party.
Barbera made the announcement after Spanish media on Tuesday published excerpts of a recording of a telephone conversation by her former advisor, Maria Jose Alcon, explaining how Alcon laundered €1,000 ($1,100) in party money.
"In this country the only thing that works is corruption," Alcon can be heard telling her son in the police recording made a year ago which dominated headlines on Tuesday.
The recording was made as part of a probe into a suspected kickback scheme that operated in the eastern region of Valencia, a PP fiefdom until 2015 when voters turned to the left in regional elections.
The authorities are looking into allegations that companies, mostly from the building sector, paid commissions in exchange for public works contracts which helped finance the PP in the region.
In the recording Alcon tells her son the party was full of "black" money and suggests one of Barbera's secretaries requested the operation to launder it.
The investigating judge in the case on Monday placed the PP under official investigation for money laundering and asked to question Barbera.
The former Valencia mayor told a news conference on Tuesday the allegations against her were "unfounded" and "completely false" and she had not committed any crime.
The scandal erupted in January, two weeks before the PP's headquarters in Madrid were searched as part of another corruption probe which tainted several people close to the head of the party in the region, Esperanza Aguirre, prompting her resignation.
PP tops corruption list
The two scandals came in the wake of a December 20th general election which saw the PP place first but lose its absolute majority in parliament, forcing it to forge alliances to govern.
The election resulted in a fragmented parliament, with power divided among four main parties, including two new formations - far-left Podemos and centre-right Ciudadanos amid a focus on fighting corruption.
But the PP is isolated. The main opposition Socialists along with Podemos and Ciudadanos refuse to back the party because of graft scandals.
"Someone who can not clean his home, can not do it in Spain," Ciudadanos leader Albert Rivera said of Rajoy.
A "Dictionary of Corruption" published last month counted 175 major cases of political corruption in Spain in the last 30 years.
Just half of these cases involved the embezzlement of at least eight billion euros of public money, according to its authors.
The PP is implicated in 68 of the corruption cases the dictionary cites while the Socialists are involved in 58.
"In Valencia and in Madrid, the PP enjoyed absolute majorities for 20 years... This created networks which believed that they could count on impunity," a recently elected PP lawmaker, who spoke on condition he not be named, told AFP.
He also blamed "an absence of control mechanisms" for the graft scandals. Irregular financing of political parties only became illegal in 2015.
Voters punished the conservatives in regional and local elections last year. The PP lost power in five regions including Valencia.
Acting Prime Minister Mariano Rajoy, who has headed the PP since October 2004, refuses to assume political responsibility for corruption, saying only he could have fought it "more efficiently".
In the PP "there is solidarity" around him but "our voters need him to leave" to allow for a clean up of the party, the PP lawmaker told AFP.
By Michaela Cancela-Kieffer / AFP