Conan O’Brien’s manager, Gavin Polone, said that a whirlwind negotiation of only about 10 days led the late-night star to leave network television and jump to the cable network, TBS.

Matt Sayles/Associated Press

“They called us about a week and a half ago,” Mr. Polone said, in outlining how the negotiations began.

The Turner Entertainment president, Steve Koonin, laid out the network’s offer to give Mr. O’Brien a show at 11 p.m. weeknights, but Mr. Polone said that the Conan team had an immediate reaction: “You guys already have an 11 p.m. show.”

He was referring to the current 11 p.m. late-night show on TBS, hosted by the comedian George Lopez. Mr. Polone said that Mr. Koonin told him everything had been worked out, and that Mr. Lopez had agreed to slide his show back to midnight to make room for Mr. O’Brien.

But that script was awfully familiar to the Conan O’Brien side. “That sounded very similar to Jeff Gaspin coming to Conan and asking him to move back to midnight to make room for Jay,” Mr. Polone said.

In the turbulent early weeks of January, NBC’s entertainment chief, Mr. Gaspin, went to Mr. O’Brien to ask him to move the “Tonight Show” to 12:05 a.m. to free up the preceding half hour for Jay Leno to move back to late night (in a 30-minute show) after the quick failure of his 10 p.m. comedy hour.

Mr. O’Brien refused and negotiated his exit from NBC. In the months since, his representatives were known to be speaking mainly to Fox Broadcasting about a new show for that network.

Mr. Polone said he went to Mr. O’Brien to inform him of the TBS offer. “Conan said, ‘We’re not putting ourselves in the position of shoving somebody out of his show.’ ” That blocked the potential deal for a brief time.

But that position changed after another phone call. Mr. Polone said that Mr. Lopez himself called Mr. O’Brien personally. “George called Conan to sell Conan on this idea. He was all for it. It really was George who made this happen.”

With Mr. Lopez on board, talks became serious very quickly with TBS, Mr. Polone said. TBS emphasized how young their audience was, a match with Mr. O’Brien’s core viewers. “The lead-ins would be shows like ‘Family Guy’ and ‘The Office,’ which is great for Conan,” Mr. Polone said. Mr. Lopez has the youngest audience in late night, with a median age of 33.

The negotiations moved rapidly because, Mr. Polone said, TBS agreed quickly to almost every request. “We’d come back with complex details and they’d apologize and say they might not be able to get back to us for two hours.”

TBS also promised “the biggest promotional campaign in television history” for Mr. O’Brien, using some of TBS’s most popular properties, including this year’s NBA playoffs and the Major League Baseball playoffs.

Mr. O’Brien will continue to produce his show in Los Angeles, Mr. Polone said.

He declined to comment on what happened with the negotiations with the Fox network, except to say that they had been continuing. But several executives who have been familiar with that process said that complications had made those negotiations difficult to conclude.

Mainly Fox’s affiliated stations have deals in place for syndicated programs — mostly repeats of shows like “The Simpsons” and the same two comedies that play on TBS, “The Office” and “Family Guy.” The stations have already paid for those shows and sold advertising for them.

The stations have also been through a financially crippling year because of the national recession and many were resistant to giving up the profits they would experience with the syndicated repeats. (Fox and the affiliates were also facing contentious negotiations over retransmission rights to cable networks, a source of income the two entities will battle over in terms of who gets how much.)

Mr. O’Brien was likely to reach only about 60 percent of the country with a first broadcast at 11 p.m. The rest of the country would be reached at later hours, diminishing his chances to hit a big rating – at least initially. Fox was promising to expand the coverage to full clearance at 11 p.m. in about three years, several parties to the talks said.

But with TBS, Mr. O’Brien will reach almost every home in the nation immediately. That made the deal more attractive.

Stepping away from a broadcast network may mean that he will not get a full chance to face off with Mr. Leno and NBC, a prospect he might have liked given the circumstances of his departure.

But what it does set up is a new kind of heavyweight match in late night. Now Mr. O’Brien will be face to face with the two big stars of late night in cable, Jon Stewart and Stephen Colbert of Comedy Central.

All three men are close friends; now they will be measured directly against each other in the ratings.