By Colleen Jenkins

GREENSBORO, North Carolina (Reuters) - Former Senator John Edwards' defense is set to begin presenting its case on Monday trying to rebut government charges the two-time presidential candidate violated campaign finance laws.

Edwards, 58, is accused of allowing more than $900,000 in secret donor money to be used to conceal his pregnant mistress during his 2008 run for the Democratic presidential nomination.

The one-term North Carolina senator faces possible prison time and a fine if convicted of any of six counts, including conspiring to solicit the money, accepting more than the $2,300 allowed from any one donor and failing to report the payments as contributions.

The trial in Greensboro, North Carolina, is entering its fourth week after U.S. District Court Judge Catherine Eagles refused on Friday to dismiss the charges against Edwards following the close of the government's case.

Prosecutors wrapped up their case after presenting nearly three weeks of evidence and two dozen witnesses.

The judge said jurors should decide if the donor money constituted campaign contributions and whether Edwards, the Democratic vice presidential nominee in 2004, knew he was breaking the law.

The defense says the money from Texas trial lawyer Fred Baron and heiress Rachel "Bunny" Mellon was used to hide Edwards' affair from his cancer-stricken wife, not to influence the outcome of the election.

Defense attorneys said they expected to take about a week to present their case. Their witness list includes 65 potential witnesses, with Edwards' mistress, Rielle Hunter, and his eldest daughter, Cate Edwards, among those who could be called to testify.

(Reporting By Colleen Jenkins; Editing by Eric Beech)