After scribbling some thoughts in his battered black spiral notebook, Tom Brokaw practices his introduction with 13 minutes till airtime.

"Security is extremely tight, and so are the poll numbers in the presidential race," he reads off the teleprompter in NBC's cramped ninth-floor skybox.

"Can I make a few suggestions here?" says Karl Rove, the White House strategist seated to Brokaw's right. " 'The Bush campaign is gaining strength . . . ' " Brokaw plays along: "The president surging in Florida, catching up in Iowa . . . " "Can you run my copy? The answers to the questions?" Rove asks the floor director.

Brokaw laughs, seeming very much the old pro here in Madison Square Garden as he presides once again over the quadrennial ritual. Yet Brokaw is interviewing Rove not for NBC but for its cable sibling MSNBC, with a fraction of the audience, because the broadcast networks have all but abandoned the turf.

His hair is nearly white now, and although the smooth baritone is just as resonant, his enthusiasm for political conventions has faded since he covered his first, 36 years ago.

That's not because Brokaw, at 64, has lost interest in the anchor job he will surrender after Election Day, or in the political game he studies as avidly as a baseball fan scrutinizes box scores. But the political game has changed, the media business is more unforgiving, and the old gavel-to-gavel, backroom-dealing, anything-can-happen convention is a distant memory.

Being on NBC for just three prime-time hours this week is "very frustrating," Brokaw admits, and he blames "the paid consultants and image makers who have drained the convention of all vitality. It seems disconnected from people's lives, it's so managed, manipulated, staged and marketed to death.

"God forbid there should be any fight over a platform. It's done in a secret vault five days before the convention starts. Delegates on the floor, either by instinct or instruction, are encoded not to say anything that will be off-message in any way."

All this is a far cry from the raucous political gatherings Brokaw watched while growing up in South Dakota in 1956 and 1960, when, he says, "I got the fever bad."

As he recalls telling a GOP convention manager the other day: "You worked it out so all I can say is, 'Good evening, we have to go to the podium now.' " The official did not disagree. "It's a marketing exercise now, aimed at selling the Republican ticket to the country. To some degree, we do feel boxed in."

But is that the fault of the parties or of NBC, CBS and ABC, whose news divisions are so consumed with turning a profit that they have all but ceded the conventions to cable and public television, signaling to viewers that these events must not be very important? If the networks would rather ring the corporate cash register with sitcoms and reality shows, how can they blame the parties for packing their best speeches into what little airtime they are allotted?

Brokaw responds that when Bill Clinton gave a dazzling speech on the first night of the Democratic convention in Boston, the ratings still dropped by 50 percent from the earlier entertainment programming. "It's not as if the country is saying that the terrible people at the networks are depriving us of the chance to see what we want to see."

Still, it's hard to watch Brokaw immersing himself in a convention for the 20th and last time without thinking that an era is passing as surely as when Chet Huntley and David Brinkley left the nightly newscast he now anchors. But you can't get the question out without a preemptive answer from Brokaw, as firm as it is final.

"No twinge. No second thoughts."

It is Sunday afternoon, the day before the convention starts, and Steve Capus is producing the "NBC Nightly News" -- from Athens.

Though he's still immersed in covering the Olympics, Capus believes the day's top story is the 200,000 anti-Bush demonstrators who have marched across Manhattan without disruptions. Brokaw agrees.

"When the Republicans made the decision to come to New York, they made a statement about September 11th, about New York City as a backdrop, so it's not surprising there are these types of protests," Capus says. "The show of force, the magnitude we've seen, is the biggest thing going today."

Brokaw, wearing a black T-shirt under his suit jacket, takes a call from correspondent Andrea Mitchell. He goes over some poll numbers that he wants to ask about on the air.

"You don't want to just bloviate, fill up the air with speculation," Brokaw explains. "It reminds me of the day before the Super Bowl when everyone's an expert, everyone's got a theory."

An hour and 15 minutes before the newscast, Brokaw starts writing a closing commentary. He had wanted to do something about how conventions hardly seem to matter anymore, but his old friend Bob Schieffer had done a similar piece on CBS that morning.

Instead, he types into his gray laptop: "The president's team knows that it can't get back to the White House by taking only hard right turns, so it has as three of its featured speakers Republicans who have been successful by navigating the middle of the road, as well as the right-hand side: Governor Arnold Schwarzenegger of California; Rudy Giuliani, New York's former mayor; and Senator John McCain. . . . Streetwise New Yorkers may call that the political equivalent of a popular con game in this tough town, three-card monte."

The networks may be losing interest, but Brokaw is determined to keep the dealers honest.

Of the mega-anchors who took over in the early 1980s, he is the first to walk away from the pinnacle of broadcasting success.

Dan Rather and Peter Jennings are soldiering on, but Brokaw has decided he would rather hand the baton to Brian Williams and spend more time fly-fishing and relaxing at his Montana ranch, while also writing magazine articles and doing projects for NBC.

He has been a Los Angeles reporter, White House correspondent and "Today" anchor. He has topped the bestseller list with "The Greatest Generation." He has covered wars, elections, impeachment, 9/11. But conventions have a special place in his heart.

At the 1984 Democratic conclave, the first one he anchored, Brokaw recalls making deals with Mario Cuomo and Jesse Jackson. After their speeches, they would come up to the booth and talk to him first. "Those were big coups for me," Brokaw says. "Then the management gurus took over."

This week, when he tried to book McCain, he was told that the Arizona senator would be making one appearance on each network, and that Brokaw was slated for Wednesday. And one of Rove's "layers of handlers," says Brokaw, asked if he would supply the questions in advance.

As he prepares for Monday afternoon's MSNBC show after getting a quick haircut in the makeup booth, Brokaw asks producer Meaghan Rady: "Did I tell you what we wanted up from the NBC poll?" Scribbling on an index card with a silver pen, Brokaw asks for graphics showing poor numbers for the president on Iraq, the economy and whether the country is on the right track.

While Brokaw and Rove banter like old friends as airtime approaches, the conversation turns serious when the red light goes on. Noting some recent comments by Bush, Brokaw asks: "If you were a parent of a child who had been lost in Iraq . . . and you heard a president say it was a miscalculation on my part or it was a 'catastrophic success' . . . wouldn't you be outraged?"

He hits Rove with the poll numbers, then says: "Whatever happened to that flight suit the president was wearing and that big banner" that said "Mission Accomplished"? Then it is on to the Swift boat ads and the platform plank against gay marriage. Rove fields the questions smoothly and is smiling when he leaves.

Tim Russert, the Washington bureau chief, walks into the skybox to record some remarks. "Good job with Rove, Brother Tom," he says.

"He's good," Brokaw replies. The interview will be excerpted on "NBC Nightly News" because the network has no other live coverage on the convention's opening day.

Brokaw records the headlines played at the top of the newscast, and a 90-second commentary that will be beamed to Sprint cell phone users. Brokaw starts, but producer Rady tells him to look up. "Am I on camera? They can look into their phone and see me?"

Why would Brokaw bother with such a tiny audience? "As my friends will tell you, I'd talk politics in a phone booth. I like the game."

Thirteen staffers, led by executive producer Mark Lukasiewicz, are gathered around a speakerphone in a chilly NBC trailer on Eighth Avenue.

It is 10:30 a.m. Tuesday, and Brokaw begins the conference call -- which includes executives from MSNBC, CNBC and NBC-owned Telemundo -- by urging everyone to "strike a balance" between covering the convention and letting the Republicans hijack the show.

"This is not about going through 9/11 again," Brokaw says from his Midtown office. "It's about what's been going on since then, in the war on terrorism and the war in Iraq. It's not enough to just put your hand over your heart and shed a tear."

MSNBC President Rick Kaplan chimes in: "One thing we have to be on the hunt for is where are the Tom DeLays and all the rest of them," who are "taking a back seat" to the parade of less conservative speakers. Brokaw says they should prepare graphics with excerpts from the party platform.

NBC News President Neal Shapiro says they should make a point of checking in with rank-and-file delegates as a contrast to speakers like Giuliani and Schwarzenegger.

"We've talked about that at great length, about the social moderates on the stage," Brokaw says, sounding a tad defensive.

The problem for tonight, a staffer explains, is that the Bush campaign has "packed the program" when the network is on from 10 to 11, with Schwarzenegger coming on at 10:03 and followed soon afterward by Laura Bush, who will "take us until 11 o'clock."

Steve Capus, back from Athens, runs through the "Nightly News" lineup: Brian Williams with an overview, Campbell Brown on gay marriage, Lisa Myers on fat-cat donors and excerpts from an interview Brokaw did an hour earlier with the president's father. He notes that a group of anarchists may try to force their way into the Garden at 7 p.m.

"We've gotta keep Tom hot," Capus says, meaning able to go live after "Nightly News" if trouble breaks out.

An unscripted moment occurs when Brokaw is interviewing Bush confidante Karen Hughes on his MSNBC show -- the power goes out. The network stalls by rerunning a "Today" interview with Bush while Brokaw moves to a Telemundo booth down the hall.

Later, Brokaw reads a promo spot: "Tonight on NBC Nightly News . . . Vice President Cheney speaks, he answers critics -- " Brokaw mangles the line, stops and sticks out his tongue. He does it again without missing a beat.

Campbell Brown calls. "Are they going to take this to the floor, the gay caucus?" Brokaw asks about the gay marriage issue. "They are? I think we should say that. . . . I'll put it in the lead-in."

Brokaw straightens his tie and opens the newscast. He says the Republicans are rolling out Schwarzenegger and the first lady "on a day when President Bush backed off a statement that he made to Matt Lauer on the 'Today' show that he didn't believe you can win the war on terror." This has the dual effect of highlighting a rhetorical flip-flop and plugging a colleague's interview.

In an echo of the morning meeting, Brokaw tees up the Brown story this way: "What you won't see tonight is the unhappiness among some of these delegates with the party's platform on gay marriage and civil unions. The platform is firmly against both."

Afterward, as an assistant brings out a plate of food, Brokaw and Russert are reading an advance draft of Laura Bush's speech and remarking on how long it seems. "You know what?" Brokaw jokes. "Arnold is starting off at 10 o'clock, he's going to hand it off to the daughters, and they'll hand it off to Laura, and we're going to have two minutes at the end."

It turns out to be no joke. When Brokaw and the broadcast networks come on at 10, Schwarzenegger is already at the podium, the hall is roaring and the anchor has exactly one minute to set the scene. Brokaw and his team wind up getting three more minutes after the first lady closes out the hour.

No wonder the thrill is mostly gone.

"Will I miss putting on nine different gadgets and going through seven metal detectors and walking up eight flights of stairs?" he says. "Do I want to spend the rest of my life doing this? No."

NBC's Tom Brokaw surveys the Madison Square Garden convention floor. In 1976, he interviewed Atlanta Mayor Maynard Jackson at the Democratic convention, below. Tom Brokaw with White House strategist Karl Rove at the Republican convention in New York, and flashing his credentials under one of network TV's most familiar faces. Of his impending retirement he says: "No twinge. No second thoughts."