A source "familiar with the situation" said Lance Armstrong confessed to Oprah Winfrey during an interview that he used performance-enhancing drugs, The Associated Press reported.

The source spoke on condition of anonymity because the interview won’t be broadcasted until Thursday on Winfrey’s network, the wire service said.

Armstrong also might pay back part of the money he received from the U.S. Postal Service, which sponsored the cyclist and his team while he was winning six of his Tours de France, a source familiar with the situation told CNN Monday night.

The source said Armstrong was in negotiations to repay some of the money.

A spokeswoman for the agency said: "We are not in a position now to discuss any of the legal issues associated with these developments and the prior relationship between the U.S. Postal Service and Mr. Armstrong, but we will do so at an appropriate time."

Armstrong won the Tour de France a record seven straight years, beginning in 1999. The postal service terminated its sponsorship in 2004.

Armstrong sat for the interview Monday with Winfrey and was emotional at times during session, the source, who was familiar with the interview, told CNN.

Armstrong was accompanied to the interview by a group of advisers and close friends, the source said.

Tim Herman, one of Armstrong's lawyers, had no comment about the interview.

Winfrey tweeted after the interview: "Just wrapped with @lancearmstrong More than 2 1/2 hours. He came READY!" The interview will be edited down to 90 minutes, Winfrey has said.

"We are not confirming any specific details regarding the interview at this time," a spokesperson for OWN said Monday night.

The disgraced cycling legend earlier apologized to the staff of the cancer charity he started, a publicist for Livestrong Foundation said.

Armstrong was tearful during the 15-minute meeting and didn't address the issue of steroid use in cycling, Rae Bazzarre, director of communications for the foundation, said.

Bazzarre added that Armstrong offered to the staff a "sincere and heartfelt apology for the stress they've endured because of him."

He urged them to keep working hard to help cancer survivors and their families.

Armstrong's sit-down in his hometown of Austin, Texas, with Winfrey was his first interview since he was stripped of his seven Tour de France titles in October in a blood-doping scandal.

For more than a decade, Armstrong has denied he used performance-enhancing drugs, but he was linked to a doping scandal by nearly a dozen other former cyclists who have admitted to doping.

What Armstrong said or did not say to Winfrey could have ramifications.

Some media outlets have reported that Armstrong has been strongly considering the possibility of a confession, possibly as a way to stem the tide of fleeing sponsors and as part of a long-term redemptive comeback plan.

But such a confession might lend weight to the lawsuits that could await him.

The interview will air at 9 p.m. ET Thursday on the Oprah Winfrey Network. Winfrey has promised a "no-holds-barred" interview, with no conditions and no payment made to Armstrong.

But the speculations swirled Monday.

"I don't think we're going to get an out-and-out confession," says CNN sports anchor Patrick Snell. "I think we're going to get something like, 'This is what went on during this era of trying to compete at the highest level.'"

Armstrong, 41, has repeatedly and vehemently denied that he used banned performance-enhancing drugs as well as illegal blood transfusions during his cycling career.

Winfrey will ask Armstrong to address the U.S. Anti-Doping Agency's October report, which said there was overwhelming evidence he was directly involved in a sophisticated doping program, a statement from her network said last week.