A new center of power has emerged inside John F. Kerry's presidential campaign, with several veteran Democratic operatives moving quickly to consolidate their influence and effectively take over the nominee's daily message and strategy in the six weeks until the election.

In recent weeks, an influx of talent has transformed the top leadership of the campaign: Joe Lockhart, a Clinton White House spokesman, is now overseeing Kerry's efforts to shape his themes against Bush and sharpen his defense against Republican attacks. John Sasso, a sharp-elbowed operative with long ties to Kerry, is running a large part of the daily operation from Kerry's campaign plane. Michael J. Whouley, whom Kerry has described as a "magical" strategist, is making the calls on where to spend the party's money and the candidate's time, according to a half-dozen campaign sources.

Robert Shrum, the most powerful voice inside the campaign for much of the year, has seen his influence diminish significantly in the shake-up, they said. Mary Beth Cahill, the campaign manager, remains in charge of day-to-day operations at headquarters, but some Democrats say her strategic influence has been somewhat diluted by the elevation of other advisers.

Democrats see the moves as a last chance to craft and execute a message for the fall campaign after their nominee's disappointing performance over the past month. The changes are an echo of a staff shake-up that Kerry made almost a year ago, when his campaign was floundering and beset by criticism similar to what he has faced in recent weeks.

At the same time, Tony Coelho, who was chairman of Al Gore's 2000 presidential campaign, is pushing Kerry to trim his roster of consultants and pick one strong leader to manage the final weeks of the campaign. "There is a sense of disarray on that campaign that everyone is talking about," he said. "You have a great deal of creative talent coming in and a great deal of experience, but no leader of the campaign. And if Kerry tries to be that leader, they're in trouble."

Instead, the campaign is managed by something of a leadership-by-committee with Lockhart, Whouley and Sasso on top along with Cahill. Assisting them are recently arrived Clinton White House veterans Michael McCurry, Joel P. Johnson and Douglas Sosnik, who advise on message and electoral strategy.

The campaign dismisses the notion that a "shake-up" has taken place, saying that the recent additions are part of a long-standing plan to add talent as Election Day neared. Yet interviews with more than a dozen Democrats inside or close to the campaign showed Kerry has made significant changes throughout upper management -- changes he was advised several months ago to make.

"Mary Beth Cahill is running this campaign, and she's doing a spectacular job," Kerry said Wednesday in an appearance on "Imus in the Morning." He was responding to a question from host Don Imus, who asked, "Who is running this campaign?"

That question has hung over the campaign for several months to varying degrees, even in the best of times. Many people inside and outside the campaign had assumed it was Shrum, a ubiquitous figure at Kerry's side who has helped elect or reelect nearly one-third of all Democratic senators, including Kerry. But Shrum was described by several campaign aides as spending too much time protecting his influence over such things as television ads, daily speeches and personal time with the candidate, and not enough drawing in some of the party's best and brightest over the summer and responding rapidly to incoming fire.

These sources -- who spoke on the condition of anonymity because Kerry has not authorized them to discuss the internal workings of the campaign -- said Shrum and Cahill have taken much of the blame -- notably from Kerry himself -- for Kerry's failure to respond faster and more forcefully to ads by Navy Swift boat veterans critical of his military service. Cahill retains much of her authority; Shrum now is handling ads, some speech work and debate preparation but much less strategy.

While some Democrats have long hoped to see Shrum's influence curtailed, his consulting firm remains central to the campaign. Partners Michael Donilon and Tad Devine still are major strategists in Kerry's operation.

Some campaign aides blamed Kerry spokeswoman Stephanie Cutter for blocking seasoned communications pros such as Lockhart from coming aboard earlier. But she had little control over personnel matters, and many of the top party spokesmen such as McCurry and Lockhart rebuffed earlier requests to join the campaign, aides say.

Cahill, Shrum and Cutter all have close ties to Sen. Edward M. Kennedy (D-Mass.), whose fervent public support for his junior colleague is seen as crucial to Kerry's campaign before and during the Democratic primaries. Kennedy recommended that Kerry hire Cahill last November to replace campaign manager Jim Jordan when Kerry's once-front-running campaign was imploding. Cahill, Shrum and Cutter received enormous credit for turning around the campaign and leading Kerry to what turned out to be a romp to his party's nomination.

But Lockhart, Whouley, Sasso and Cahill are "essentially running the campaign" now, one high-level adviser to the campaign said, a sentiment echoed by numerous sources within and close to the campaign. Whouley is stationed at the Democratic National Committee and is playing an equally important role because the final weeks are much about trench warfare, his specialty.

Paul Begala and his CNN "Crossfire" co-host James Carville have also been lending advice, often with a direct pipeline to Kerry. As far back as 2002, when he had dinner with Begala and Carville at the Palm in Washington, Kerry has sought their assistance and sometimes heeded their advice. Since April, several top Democrats have urged Kerry to bring in a broader cast of Clinton-era advisers such as Lockhart and McCurry. One of the top Democrats urging this was Clinton himself, said a source close to the former president.

Begala, who has been privately critical of Cahill, said Kerry aides approached him last spring about leaving CNN and taking a top position with the campaign. "I nearly did," Begala confirmed yesterday, "but it didn't work out in the end."

Shrum persuaded Kerry to stick with his current team, one of several times Kerry has allowed staff to talk him out of key decisions, other aides said. The logic seemed smart at the time: Why change a winning team? It was not until his August drop in the polls that Kerry encouraged greater involvement from the Clinton people. He was frustrated by the slow response to the Swift boat ads and told friends that he wanted to fight back but that Cahill and Shrum talked him out of it, a campaign aide said. Shrum and Cahill said polls showed that negativity does not work. Some Democrats say this was the biggest miscalculation of the campaign.

Several sources in the campaign say a turning point occurred recently, when Kerry held a conference call with Bill Clinton and several aides as the former president was preparing for open-heart surgery at a New York hospital. In the call, Clinton, who had always been wary of Shrum -- Shrum had no involvement in Clinton's winning campaigns -- was critical of Kerry's passivity in recent months, characterized by his restrained attacks on Bush during the Democratic National Convention and his slow response to the Swift boat ads. Cahill and Shrum had advocated both positions. Kerry, who sources say reveres Clinton's strategic mind, has often talked about not repeating the mistakes of Gore, whose inner circle was also dominated by Shrum and largely devoid of Clinton people.

In the wake of the Swift boat ads, Kerry had largely deputized Lockhart to oversee the day-to-day communications and message strategy of the campaign -- two of the most important jobs. "He's the chief strategist," one aide said of Lockhart. McCurry is, in the words of one aide, "the adult on the plane," as far as implementing the day-to-day communications strategy.

Sasso has taken the role of "uber adult" on the road, the unofficial "best buddy" candidates traditionally have at their side, but that Kerry has often lacked. Sasso, who initially ran Michael S. Dukakis's campaign in 1988 and served as the former Massachusetts governor's chief of staff when Kerry was Dukakis's lieutenant governor, is a widely respected manager. Democrats outside the campaign are looking to him to unite the various moving parts and changing roles in the campaign. Sasso and Lockhart are tasked with keeping Kerry's multitude of advisers at bay.

"It's obvious that they're trying to beef up the plane, that they need some help out there," said Democratic strategist Bill Carrick, a longtime adviser to Rep. Richard A. Gephardt (D-Mo.) who has no role in the Kerry campaign. Carrick calls Sasso "the ultimate grownup, someone who goes back a long way with Kerry and someone Kerry will obviously listen to."

One of the abiding truths about Kerry -- and one that is often frustrating to his aides -- is that he will listen to anyone. He is known as a political loner, but he is also constantly on the phone and will take counsel at any time from any number of parties, be it fellow senators, longtime friends, advisers in ill-defined roles such as Shrum or freelancers such as Begala. Kerry is not a micro-manager, friends say, but he is prone to engaging in a vast and drawn-out process by which his decisions are informed.

"This is what works for John," said one longtime aide who is not involved in this campaign, "and we try to be respectful of it. But it can create a greater sense of chaos than is probably necessary."

Michael McCurry, center, who was press secretary for President Bill Clinton, has joined John F. Kerry's campaign as a senior adviser.