Greensboro, North Carolina (CNN) -- John Edwards knew that a wealthy benefactor was giving money to help cover up his affair with Rielle Hunter, a former speechwriter testified Tuesday during the corruption trial of the former presidential candidate.
Prosecutors say the North Carolina Democrat used donor funds to hide Hunter and their daughter, Quinn, in an effort to keep his candidacy viable.
Edwards broke federal law, they allege, by accepting about $725,000 from heiress Rachel "Bunny" Mellon for that purpose and more than $200,000 from Fred Baron, a now-deceased Texas lawyer who was his finance chairman.
He has pleaded not guilty to the charges.
Wendy Button, the former speechwriter, said she worked with Edwards during the summer of 2009, helping him craft a statement admitting paternity for Hunter's child.
"While I never asked Fred Baron to spend a dime, I stood by and watched him support Quinn," he said in an early draft, Button testified.
Edwards changed that line to then read: "Some people without my knowledge supported Quinn," she said.
And when he released the final statement in January 2010, any mention of financing for the cover-up was taken out altogether.
Edwards told his former speechwriter he did not find out the other donor, Mellon, was sending checks until much later, Button testified.
Edwards faces six felony courts, including conspiracy and making false statements.
The defense team for the former U.S. senator has argued that Andrew Young, an Edwards aide, had largely used the money for his own personal gain while also paying for Hunter's medical expenses during her pregnancy to hide the affair from Edwards' wife. Donations for that purpose, the Edwards team has argued, cannot be considered in violation of campaign finance laws.
Young admitted during questioning that he used some donations for his own personal benefit -- particularly to fund construction of a home that included a pool and a theater.
Earlier Tuesday, an Edwards donor testified that he told the Barack Obama campaign to believe rumors of Edwards' affair as early as June 2008.
Prosecution witness Tim Toben, a developer and green energy entrepreneur, said during cross examination that during a dinner with Edwards, the candidate was optimistic about his chances of his being selected as Obama's running mate.
The message from Edwards was that if he were to be offered the position, he would take it, Toben testified.
The witness said he found the idea "astonishing," given the then-rampant rumors of Edwards' affair and child with Hunter.
After the dinner, Toben called the North Carolina director of the Obama campaign, he testified. He told it the reports about Edwards' affair were true and encouraged the campaign to vet the information thoroughly as it decided on its pick.
Toben also testified about an alleged sex tape involving Edwards and Hunter, which will not be shown to the jury, and whether Young had ever suggested he wanted to sell it. Young thought about selling the video, but changed his mind, Toben said.
Once a grand jury started an investigation into the events surrounding the affair, Toben sent an e-mail to Young, asking: "Wonder what that tape is worth today?"
If convicted, Edwards could face up to 30 years behind bars.