MADRID — A Spanish court has convicted businesspeople and former conservative politicians in the eastern region of Valencia of graft and money laundering, further tarnishing the image of the party recently ousted from power over a previous corruption ruling.

The National Court found 18 of 20 defendants guilty of participating in a kickbacks-for-contracts scheme that, according to Monday's ruling, helped finance the campaigns of the Popular Party in national, regional and local elections.

A separate ruling last month that fined PP as a beneficiary of the scheme in other parts of the country forced Mariano Rajoy out of the prime minister's office via a parliamentary vote led by the Socialists' Pedro Sanchez.

Rajoy, who wants to step down as the conservative party's leader, announced Monday a July 20-21 congress to elect his successor.