STORY: Donald Trump's lawyer on Thursday accused star witness Michael Cohen of lying at the former U.S. president's trial about a 2016 phone call about a $130,000 hush money payment to a porn star.

Cohen, who was once Trump's trusted personal lawyer, claimed he spoke to his former boss about plans to buy Stormy Daniels' silence about what she claims is a 2006 sexual encounter with the then-reality TV star.

Trump's attorney, Tod Blanche, said to Cohen, "that is a lie. You can admit it!"

"No sir I can't, because I am not certain that is accurate," Cohen responded.

The exchange followed several hours of questioning by Blanche designed to cast Trump's former fixer as a spiteful turncoat eager to see his former boss behind bars.

Cohen testified he paid off Daniels, and that Trump reimbursed him, falsely logging the reimbursements as legal expenses.

Trump is charged with illegally falsifying business records to hide the payments.

The Manhattan district attorney alleges Trump wanted quash a sordid story that threatened his 2016 bid for the White House.

TRUMP: "This trial is a scam, and it's a sham, and it shouldn't happen. Thank you very much."

Trump has pleaded not guilty, denied the affair, and called the prosecution politically-motivated to hurt his presidential campaign.

Donald Trump's lawyers sought to undermine Cohen's credibility on Thursday, highlighting his past record of lying, and his statements celebrating Trump's legal troubles.

Trump's lawyer Todd Blanche played jurors audio clips of Cohen saying the case "fills me with delight" and that he felt "giddy with hope and laughter" imagining Trump and his family in prison.

Cohen's testimony has been corroborated by other evidence, including handwritten notes outlining Cohen's reimbursements, and a surreptitious recording made by Cohen of Trump seeming to discuss a hush money payment made by the National Enquirer tabloid to another woman.

Cohen is set to return to the witness stand next week.