Bild newspaper reported on Saturday that Steinbrück's wife Gertrud received an anonymous letter accusing the family of employing a Filipino cleaner illegally. The sender threatened to expose the details 14 days before the election on September 22nd.
Steinbrück denied illegally employing the cleaner. She said she had employed a cleaner in Bonn in 1999 to whom they gave social security insurance through her husband - who is the head of the Social Democrat (SPD) party.
But when the cleaner later lost her job in Germany, Steinbrück offered her a contract, which she declined. The Steinbrücks referred the blackmail attempt to the police.
Steinbrück told newspaper the Saarbrücker Zeitung: “It has got nothing to do with the other parties in the election.” He said he believed the person who sent the letter knew him from Bonn. He described the attempt as “beyond belief” and added that it would not affect his election campaign.
The letter, addressed to Gertrud Steinbrück, said that she should get her husband to withdraw his candidature for chancellor on personal grounds.
But Mrs Steinbrück told the newspaper: “The Steinbrücks…will not be blackmailed.”
She said the cleaner was employed in Bonn in 1999 to help her mother who died in 2003. The family had recently moved to Bonn as Steinbrück had been made economy minister in the North Rhine-Westphalia government.
SPD chairman Sigmar Gabriel gave Steinbrück his full backing after the attempt was made public. “This blackmail attempt is the absolute low point of the election campaign so far,” he told the Bild on Sunday.