GREENSBORO, N.C. - John Edwards' first reaction when he learned his mistress may be pregnant was to downplay the chances he was the father, calling the woman a "crazy slut," his former close campaign aide testified Tuesday.

It was summer 2007 and Edwards was in the midst of a presidential bid. Andrew Young testified that the former North Carolina senator hatched a plan to funnel money from rich friends to provide the woman a monthly allowance, even though Young said he doubted it was legal.

Months later, as word of the candidate's affair began to leak in the run-up to the Iowa caucuses, Young said Edwards asked the aide to falsely claim paternity of the baby.

Young has been the lone witness during the first two days of Edwards' criminal trial. Edwards, 58, has pleaded not guilty to six counts related to campaign-finance violations involving nearly $1 million in secret payments provided by two wealthy donors as he sought the White House in 2008.

Young said Rielle Hunter told Edwards she was pregnant in June 2007, weeks later than the aide originally claimed in a tell-all book published in 2010. Young said Edwards told him to "take care of it," meaning the pregnancy.

"He said she was a crazy slut and there was a 1-in-3 chance that it [the child] was his," Young testified.

Edwards directed Young to start giving money to Hunter in May 2007, after she threatened to go to the media and expose the affair, the aide said. Edwards suggested asking elderly heiress Rachel "Bunny" Mellon, who had already given generously to the campaign.

Prosecutors showed the jury canceled checks from Mellon written to her interior designer, who would then endorse them and send them to Andrew and his wife, Cheri. Starting in June 2007, Mellon would eventually provide checks totaling $750,000.

Without telling Mellon what the money would be used for beyond that it was a "noncampaign" expense, Young said she offered to provide $1.2 million over time to help pay for the candidate's personal needs. Under federal law, donors are limited to giving a maximum of $2,300 per election cycle.

"We were scared," Young said. "It was a truckload of money. ... It was crazy."

Young said he expressed concern to Edwards, a former trial lawyer, that they might be violating federal laws.

"He told me he had talked to several campaign-finance experts and that it was legal," Young testified.

The baby Edwards fathered, Frances Quinn Hunter, was born in February 2008, right after he suspended his campaign after a series of primary losses. After years of denials, Edwards eventually acknowledged paternity in 2010. The girl, now 4, lives with her mother in Charlotte.

When asked why he agreed to claim paternity and care for Hunter, Young said power was the lure.

"I wanted my friend to be president," Young said. "Being friends with the most powerful person on earth, there are benefits to that."

Edwards has denied knowing about the money provided by Mellon. If convicted on all six counts, Edwards faces a maximum penalty of 30 years in prison and as much as $1.5 million in fines.