GREENSBORO, N.C. - Lawyers for John Edwards opened their defence of the former U.S. presidential contender Monday, arguing that the nearly $1 million in secret payments from two wealthy donors to help hide his pregnant mistress as he sought the Democratic nomination in 2008 were not campaign contributions.

Edwards has pleaded not guilty to six criminal counts related to campaign finance violations. He is accused of masterminding the scheme.

Defence attorneys are attacking the foundation of the prosecution's argument that the money should be considered an illegal campaign contribution intended to influence the outcome of an election.

But even the federal government was split on that, the defence argued. The Federal Election Commission previously decided that the money was not a campaign contribution. The Department of Justice calls that decision irrelevant.

On Monday, Lora Haggard, who was in charge of campaign finance compliance for Edwards, testified that the money from heiress Rachel "Bunny" Mellon and campaign finance chairman Fred Baron has never been reported, because the FEC said it didn't need to be.

She also said Edwards was never involved in formulating, filling out or filing campaign finance reports that were sent to the FEC.

Prosecutors rested their case Thursday by playing a tape of a 2008 national television interview in which the Democrat repeatedly lied about his extramarital affair and denied fathering his mistress' baby.

A key question is whether Edwards will take the stand.

Before winning a U.S. Senate seat in 1998, Edwards made a fortune as a personal injury lawyer renowned for his ability to sway jurors. But his testimony would expose himself to a likely withering cross-examination.