Clemens and his attorney, Rusty Hardin, played a tape of a 17-minute telephone conversation between himself and McNamee, who told the Mitchell Committee and federal investigators that he had injected the right-hander with steroids and human growth hormone during a period from 1998 to 2001.
The tape of the conversation, which was recorded on Friday, was played prior to the press conference at the George R. Brown Convention Center in Houston.
In it, McNamee did not contradict his statements, but he apologized to Clemens for any pain he had caused him or his family.
"All I did was what I thought was right," said McNamee. "It wasn't right, but I did what I had to do."
During the profanity-laced conversation, McNamee asked Clemens 21 times, "What do you want me to do?"
"I just need someone to tell the truth, Mac," Clemens said.
"For the life of me I'm trying to figure out why you told guys I did steroids," Clemens said later in the conversation.
"I understand that," said McNamee, who sounded distraught at times.
"It is what it is, and it's not good," McNamee said. "And I want it to go away. And I'm with you. I'm in your corner. I don't want this to happen. But I'd also like not to go to jail, too. But it has nothing to do with you.
"I don't have any money. I have nothing. I'm not doing a book deal. I got offered seven figures to go on TV. I didn't do it. I didn't take it. I didn't do anything. All I did was what I thought was right -- I never thought it was right, but I thought that I had no other choice, put it that way."
Upon the advice of Hardin, at no point did Clemens ask McNamee to recant his testimony. If he had, Hardin said he was concerned that Clemens would appear to be tampering with a federal witness. The end result was a conversation that leaves the question of who is telling the truth unresolved.
It's unclear if McNamee knew the conversation was being taped. Under state law in New York and Texas, only one party has to give consent for a phone conversation to be taped. In this case, it was Clemens, who was at home. McNamee said he was speaking on a cellular phone.
Hardin said that because McNamee didn't deny Clemens' claims that he never used steroids, it amounted to proof that Clemens was telling the truth.
One of McNamee's lawyers, Earl Ward, countered by telling ESPN Radio in New York that "the tape adds absolutely nothing."
Clemens said McNamee initiated the conversation by sending him an e-mail. "He said his son was sick and dying. That's why I reached out," Clemens said.
After the tape was played, Clemens took about a dozen questions from a roomful of reporters, many of whom he feels have already branded him as a steroid user in light of McNamee's allegations.
"I will answer your questions, even though there's some in the audience that I'm very uncomfortable looking at right now," Clemens said, choking back emotion. "I'm just going to try and rise above it -- some of the things that have been said in my hometown especially without giving me the benefit of the doubt or looking into the details that have been said here."
Clemens then answered many of the same questions that were posed to him during the Sunday night's "60 Minutes" interview. He reiterated his stance that he accepted injections from McNamee of the vitamin B-12 and the painkiller Lidocaine. Just before the segment aired, Clemens filed a defamation suit against McNamee in Texas state court, another salvo in the escalating fight between the pair, who had worked together since they met while with the Blue Jays a decade ago. One of McNamee's lawyers, Richard Emery, said his client probably will counter sue Clemens in New York.
Clemens confirmed that he will accept the invitation to appear on Jan. 16 in front of the House Oversight and Government Reform Committee. Clemens and McNamee were asked to testify, as were Yankees pitcher Andy Pettitte, retired player Chuck Knoblauch and Kirk Radomski, the former Mets clubhouse employee who allegedly supplied McNamee with performance-enhancing drugs.
"I'm going to Congress, and I'm going to tell the truth," Clemens said. "I'm going to tell everything I know about the situations and steroids and everything else I have knowledge about, which isn't a lot. It wasn't something that was talked about in the clubhouse in a big way."
The committee planned to ask Clemens' representatives for the complete recording of the telephone conversation, said Karen Lightfoot, communications director for the panel's chairman, California Democrat Henry Waxman.
Under an agreement with the U.S. Attorney's Office in San Francisco in its investigation of the Bay Area Laboratory Co-Operative for money-laundering and selling drugs illegally, McNamee disclosed information to the feds about Clemens, Pettitte, Knoblauch and Jason Grimsley. He also provided the same information to Mitchell.
As far as the report is concerned, under McNamee's federal agreement, he can be charged with criminal violations, "including making false statements, which is a felony."
Clemens repeated his earlier statement that he did not know Pettitte had taken human growth hormone and said the two never discussed performance-enhancing drugs, except when new issues were being discussed in the media.
One reporter asked Clemens if he considered players who take steroids as cheaters.
"My deal on the whole subject is I think it's a self-imposed sentence," Clemens said. "I think that it's a short fix. I've said it many times, I think they do it to look good in the lobby in their three-piece suit. I don't think it helps you hit the baseball, run faster, or whatever and all that combined. I think it hurts your body."
"So you don't think they're cheaters?" the reporter asked.
"I didn't say that," Clemens said. "That's for them to decide. I'm not passing judgment, obviously, on anybody else."
The reporter probed on.
"Do you think Andy's a cheater?"
"I'm not passing judgment on Andy," Clemens said. "Andy's my friend. I'm not passing judgment on him."
The longer the question and answer session continued, the more animated Clemens became. At one point, Hardin, passed him a note that said, "lighten up."
"You want me to lighten up?" Clemens said. "It's hard. Thank you."
The session ended abruptly when Clemens recalled an "asinine" question about how this scandal will affect his Hall of Fame legacy.
"You think I played my career because I'm worried about the damn Hall of Fame?" Clemens said. "If you have a vote and it's because of this, you keep your vote. I don't need the Hall of Fame to justify that I put my butt on the line and I worked my tail off. And I defy anybody to say I did it by saying I cheated or by taking any shortcuts. OK?
"I made a statement through (Hardin) when it first happened. I've made a statement through my foundation and that wasn't good enough. And now I'm here doing this. I cannot wait to go into the private sector and hopefully never have to answer to it again. I've said enough."
Clemens then walked out of the room and did not answer any more questions.
Alyson Footer is a reporter for MLB.com. MLB.com national reporter Barry M. Bloom and The Associated Press contributed to this story. This story was not subject to the approval of Major League Baseball or its clubs.