WASHINGTON -- Early in the presidential race, when Sen. Hillary Rodham Clinton was still the heavy favorite, she asked former New Jersey Sen. Robert Torricelli whether the little-known political operative running Sen. Barack Obama's long-shot campaign, was any good.

"I warned her," says Mr. Torricelli, who knew what he was talking about.

The operative, David Plouffe, had helped Mr. Torricelli win his Senate seat. It was one of the most toxic campaigns in modern memory -- "unrestricted chemical warfare," Ross K. Baker, a political scientist at Rutgers University, called it -- and Mr. Plouffe demonstrated a talent for devising a campaign strategy, staying with it under fire, and doing what it took to win.

Today, still largely unknown, the fiercely competitive 41-year-old Mr. Plouffe stands at the center of one of the best-funded, best-organized Democratic presidential campaigns ever. And just as it was against Clinton, the hallmark of his plan to beat John McCain is unconventional audacity -- that, and Mr. Plouffe's characteristic determination to stick with the plan no matter how much others question it.

Conventional wisdom dictates, for instance, that Democratic presidential candidates have no real chance in a bundle of states across the South and the West. To win the White House, Democrats must focus on battlegrounds like Ohio, Michigan, Missouri and Florida.

Following the conventional wisdom is not Mr. Plouffe's style, though. His plan calls for Obama not only to hold every state that Sen. John F. Kerry won in 2004 and go all-out in the battleground states, but also to try to steal states that Republicans have carried for decades.

That same rejection of the orthodox marked his approach to the nomination battle. He was both architect and enforcer of a strategy that ignored others' advice and gave primacy to the Iowa caucuses, then plowed resources into smaller states that chose delegates after the mass of contests on Super Tuesday.

Some of Mr. Obama's staunchest backers, including major financial contributors, protested loudly against the focus on Iowa -- to no avail.

In a campaign inner circle marked by discipline and facelessness, no senior aide makes a greater point of avoiding public view than Mr. Plouffe. David Axelrod, the strategist who shapes Mr. Obama's message, often acts as a campaign surrogate on TV. Mr. Plouffe refuses to grant interviews and only occasionally speaks out publicly.

Yet he has a hand in virtually every aspect of Obama's world: field organization, advertising and fundraising. Lately, he has been meeting with Clinton donors, trying to absorb them into Mr. Obama's fundraising network.

He gave a private briefing to a group of Clinton supporters at the offices of a New York City law firm last month, previewing Obama's strategy for the general election. Sarah Kovner, a longtime Clinton backer who was in the audience, said Mr. Plouffe "was incredibly confident. Some people still had questions and they asked questions and he was persuasive."

Mr. Plouffe is famously tight with campaign money. Cab rides aren't reimbursed -- just subway fare. Staff members are asked to double up in hotels. For trips no longer than five hours, aides are expected to drive, not fly.

Mr. Axelrod tells a joke that underscores Plouffe's frugality: Bathrooms at the campaign headquarters have automatic paper towel dispensers. Wave your hand under them once, a towel comes out; wave your hand a second time, a message pops up: "See Plouffe."

When Mr. Plouffe emerges in public, sometimes it's to throw an elbow. It was he who called Mrs. Clinton "one of the most secretive politicians in America today," and questioned whether she would be "open and honest with the American people as president."

A former Clinton aide describes Mr. Plouffe's approach with rueful respect: "They did what they had to do when they had to do it. And they did it without restraint."

Sometimes, the aggressiveness has backfired. Earlier this year, Canadian television reported that an Obama economics adviser had told Canadian officials the Illinois senator's assault on NAFTA amounted to political maneuvering. In a conference call with reporters, Mr. Plouffe issued six denials in the space of 65 seconds. "There's just nothing to it," he declared.

A few days later, The Associated Press got hold of a memo from a Canadian official that showed a meeting had taken place, that NAFTA was discussed and that the Canadians came away with the impression that Mr. Obama's criticism of free trade was political posturing.

Mr. Axelrod said Mr. Plouffe suffered from "poor information flow internally."

"He went out and carried a message that he thought was true but wasn't," said Mr. Axelrod, who is partners with Mr. Plouffe in a Chicago-based political consulting enterprise.

As Mr. Plouffe looks toward November, he sees Mr. Obama as a unique candidate, with the money, volunteers and organizational skill to rewrite the election map. Carrying some traditionally GOP states makes winning Florida and Ohio less of a make-or-break proposition.

Recently, Mr. Plouffe laid out the strategy for reporters, using a mix of military terminology and sports metaphors to drive home his points.

Mentioning Virginia -- which hasn't gone Democratic in a presidential election since the Lyndon B. Johnson era -- Mr. Plouffe said: "Win Virginia and it's game, set, match [for Obama]."

Talking about registering sympathetic voters, he sounded like a battalion commander the night before an assault. "We know who these unregistered people are," he said. "We will go find them. We're going to go where they live and we're going to convince them to register."

Other Democrats believe that Mr. Plouffe can make his strategy work.

"Look at the history," said U.S. Rep. Rahm Emanuel, D-Ill., a member of the House leadership, rattling off the names of underdog candidates who preceded Mr. Obama. "Gary Hart, Howard Dean, Bill Bradley -- insurgents are supposed to have one day in the sun and lose. The establishment comes back and whacks you."

Not so with Mr. Obama, Emanuel said. "These guys won."

Mr. Plouffe, who has close-cropped brown hair and an aura of absolute confidence, got his first job in politics while a student at the University of Delaware, which he attended from 1985 to 1989 without graduating. He was hired by Democratic strategist Joe Hansen to work in a Delaware Senate race. The two became close friends -- conserving money by subsisting on two-for-a-dollar hot dogs at 7-Eleven.

When Mr. Hansen moved to Iowa to work for U.S. Sen. Tom Harkin, he asked Mr. Plouffe to come along. Mr. Plouffe was comfortable in the scrum. In the 1996 New Jersey Senate race, Mr. Torricelli won, although he abandoned a re-election bid six years later amid questions about his ethics. Larry Weitzner, an aide to then-U.S. Rep Richard Zimmer, Mr. Torricelli's Republican opponent in the '96 race, said Mr. Plouffe "was very effective at muddying the waters over the true weakness in the character of his candidate."

Federal prosecutors later investigated possible fundraising abuses, but no charges were filed.

Mr. Plouffe learned the nuances of the Iowa caucus system while working in Mr. Harkin's losing 1992 presidential bid and Richard A. Gephardt's unsuccessful effort in 2004. The knowledge proved invaluable for Mr. Obama's run.

Mr. Plouffe believed Iowa was crucial. "There was a lot of pressure on David to move outside of Iowa and develop a national strategy," said Valerie Jarrett, a longtime friend of the Obamas and a senior adviser to the campaign.

"The Iowa strategy was right for Barack because he didn't have the name recognition and campaign infrastructure to run a national campaign. ... David, in a very steady, steely way, said: 'This is our strategy and we're sticking to it.' "