John Edwards asked philanthropist Rachel "Bunny" Mellon for an additional $3 million several years after the botched cover-up of his extramarital affair, according to testimony in his criminal trial today. 

However, jurors won't hear this testimony -- after a successful objection by the defense, which argued the pricey 2011 request had no bearing on funds obtained from Mellon during the 2008 election cycle. 

Those funds, along with money from another donor, are at the heart of the federal campaign finance case against Edwards. Prosecutors are trying to prove those donations constituted illegal campaign contributions. 

Without the jury present, the librarian at Mellon's farm, Oak Spring Garden, on Monday described a 2011 phone call in which Edwards allegedly made the request of his long-time supporter. 

"The senator had talked to her about some additional money to help get him established and moving on," said Tony Willis. "She said that she couldn't. And then when she came to the library, she said, 'I really need to write a letter.'"