Former U.S. Senator John Edwards is expected to admit he is the father of his former mistress' 18 month old daughter, CBS affiliate WRAL reported yesterday citing anonymous sources.

Edwards, who has been a Democratic presidential candidate twice, has denied fathering the daughter of former mistress Rielle Hunter, and has agreed to undergo a paternity test.

The name of the girl's father is not disclosed on her birth certificate, according to the paper. A long-time aide of Edwards is believed to be writing a book in which he will unveil Edwards is the father, the paper reports.

Currently, a Federal grand jury is investigating if Edwards used money from his campaign to buy Hunter's silence. Edward's public admission may come before the end of the criminal investigation, the paper says.