NEW : Federal judge tells attorneys to expect ex-mistress to testify for government . Edwards is the ex-mistress of 30 years Democratic presidential candidate Edwards . At issue in the approaching North Carolina trial is whether money given to support Edwards ' mistress , Rielle Hunter , by the then-candidate 's benefactors should have been considered donations toward his presidential campaign . John Edwards ' upcoming criminal trial will look at whether campaign money went to her . Edwards denies any wrongdoing .
NEW : Federal judge tells attorneys to expect ex-mistress to testify for government . Edwards is the ex-mistress of 30 years Democratic presidential candidate Edwards . John Edwards ' upcoming criminal trial will look at whether campaign money went to her . Edwards denies any wrongdoing .