When lawyers for Anthony Weiner, the former Democratic congressman who faces sentencing in a sexting case that involved a 15-year-old girl, wrote to the judge this week seeking probation for their client, they made it clear that he had no excuse for his conduct.

But they also raised questions about the credibility and motivation of the teenage victim. They said that she not only had a profit motive for making contact with Mr. Weiner and exchanging lewd texts and images with him, but that she also said she had sought to influence the presidential election.

In their submission to the judge, the lawyers made it clear that such information could have an impact on the judge’s assessment of the nature and circumstances of Mr. Weiner’s crime, and of course on the ultimate sentence.

For Mr. Weiner, the disclosure of his tawdry communications with the girl was another in a long list of self-destructive acts that largely destroyed his marriage and his political career. Mr. Weiner was forced to resign from Congress in June 2011 after an explicit picture, sent from his Twitter account, became public. In May, he pleaded guilty to transferring obscene material to a minor, which carries a sentence of up to 10 years in prison.