The wife of a former aide to one-time US presidential candidate John Edwards has broken down on the witness stand while recounting how Edwards asked the couple to hide an affair he was having and justified using wealthy donors' money to do it.
Testifying at Edwards' campaign corruption trial, Cheri Young said she huddled around a phone in her home with her husband, Andrew Young, and Edwards' pregnant mistress, Rielle Hunter.
On the call, Edwards emphasised the need to preserve his 2008 campaign and keep the affair from his wife, Elizabeth, Cheri Young said. Elizabeth Edwards was battling cancer at the time.
Two suspicious tabloid reporters had already tracked Hunter from a doctor's appointment to the Youngs' home.
Edwards made the plan sound "as if it was for the good of the country", Cheri Young said.
Edwards is accused of deliberately using money from two wealthy donors to hide Hunter as he sought the White House. He has pleaded not guilty to six counts related to campaign-finance violations. He faces up to 30 years in prison and $US1.5 million ($A1.44 million) in fines if convicted on all counts.
Asked by a prosecutor why she went along with Edwards' plan, Cheri Young put her hands together, pressed them to her chin and bowed her head as if in prayer.
As she began to weep, US District Court Judge Catherine C Eagles dismissed the jury to give her time to compose herself.
Edwards sat back in his chair and put two fingers to his pursed lips. As Young dabbed her tears, the former US senator glanced at his watch.
"I felt like everything had been dumped in my lap," Cheri Young said once the jury returned.
"Everybody was on board but me. ... I didn't want the campaign to explode and for it to be my fault. I decided to live with a lie."
During the call, Edwards suggested it would only be a one-day story if Andrew Young took responsibility for the baby.
"'Nobody cares about two staffers having an affair,"' Cheri Young recalled Edwards saying.
At issue in the trial are payments from a wealthy Texas lawyer, Fred Baron, who served as Edwards' campaign finance chairman and an elderly heiress, Rachel "Bunny" Mellon.
Andrew Young, who testified last week under an immunity agreement, has acknowledged that he used for himself about $1 million of $1.2 million in payments from the two donors.
Cheri Young said she had doubts about taking the "Bunny money" and using it to cover up the affair. She said Edwards hatched the plan to have her deposit the money into an account controlled by her and her husband.
Concerned about violating the federal $2,300 limit on individual campaign contributions, Young said she reluctantly agreed after insisting on hearing Edwards say the scheme was legal.
"I heard Mr John Edwards tell me on the phone that he checked with the campaign lawyers and that this was legal," she said.