( CNN ) -- The former mistress of 2008 Democratic presidential candidate John Edwards is expected to be a prosecution witness in his federal criminal trial next month , a federal judge said in court Thursday . 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 . Edwards maintains the money was a gift . Edwards is charged with six felony and misdemeanor counts related to donations to and payments from his failed 2008 campaign . He is accused of conspiracy , issuing false statements and violating campaign contribution laws . He denies any wrongdoing . In federal court in Greensboro , North Carolina , on Thursday , Judge Catherine Eagles said that attorneys in the case should expect Hunter to testify on behalf of the government . If convicted on all counts , Edwards could face 30 years in prison and a fine of up to $ 1.5 million . His attorneys have claimed the investigation and prosecution are politically motivated , and the charges do not clearly establish any violation of election law . His lawyers have argued in federal court the money was a gift unrelated to campaign expenditures and that legally , donors can help pay for a candidate 's personal expenses unrelated to the campaign , according to a report by CNN affiliate WTVD in Raleigh , North Carolina , last October . The attorneys also said money from donors never went directly to Edwards , but was handled through third parties , WTVD said . Edwards was Sen. John Kerry 's running mate on the 2004 Democratic presidential ticket . CNN 's Joe Sutton contributed to this report .
NEW : Federal judge tells attorneys to expect ex-mistress to testify for government . Rielle Hunter is the ex-mistress of 2008 Democratic presidential candidate John Edwards . Edwards ' upcoming criminal trial will look at whether campaign money went to her . Edwards denies any wrongdoing .