(FORTUNE Magazine) – Almost everyone agrees that George W. Bush is a different President than he was two months ago. Historians, his Republican allies, even Democrats believe he has stepped up to the job just when the country needed him to. "He's done well," says House Democratic leader Richard Gephardt. "He's risen to the challenge." Historian Douglas Brinkley of the University of New Orleans concurs: "Bush has grown into the role of Commander-in-Chief by scaling an exceptional learning curve."

But some questions remain: Is this a permanent change? How will it affect the rest of his presidency? And just who is the real George Bush? The easygoing, back-slapping fellow who never showed much interest in the rest of the world? Or the highly focused, unexpectedly articulate man we've seen since Sept. 11? People who know Bush well say he has always had leadership abilities, however latent. But even they are surprised by how thoroughly he's been transformed from the workmanlike President he was into the wartime chieftain he has become. The last President to change so dramatically was Harry Truman. When Truman was thrust into the Oval Office by Franklin Roosevelt's death, he didn't even know about the Manhattan Project to develop the atomic bomb. Yet he used the weapon to end World War II and went on to devise the national security structure that sustained the long Cold War against Communism. As with Truman, one of Bush's biggest advantages is the low expectations people have of him.

Bush's archetype now isn't Truman (or George H.W. Bush). It's Ronald Reagan. In public statements Bush has characterized the war on terror as a simple black-and-white proposition--good vs. evil, us vs. them--thus giving people ample reason to rally behind him. That's very Reaganesque; remember the Evil Empire? Like Reagan, Bush communicates in straightforward phrases blended with the language of the American frontier: We want Osama bin Laden "dead or alive. We'll smoke him out of his cave."

But there's also something about Bush himself that has changed since Sept. 11. He's more comfortable in his job, more engaged. When he visited New York after the attack, he was supposed to spend 40 minutes with the victims' families. Instead he spent two hours, making direct connections with everyone, sometimes crying with them. His public remarks, formerly rare and often fractured, are more frequent and self-assured. Inside the White House he's more demanding. About the free-trade legislation he's pushing as part of his economic revitalization plan, he told staffers, "I'm going to get this done. Don't get in my way."

For a man who likes to relax (he took four weeks of vacation last summer), his days now are intense. He arrives at the Oval Office earlier than he used to (before 7 A.M.), holds more meetings, and covers more ground in each of them, often cutting them short to fit in other business. He exercises daily after falling out of the habit and eats healthier food, knowing he must keep up his energy. Bush's magnified sense of purpose has improved his performance in office. "He's become more confident and speaks with real conviction, which evokes strong conviction in others," says Georgetown University professor Stephen Wayne. "He has developed a take-charge approach, and that's what we want in a leader at a time of crisis."

While Bush may never be a great communicator, he manages to be clear and credible. His prepared speeches, especially his televised address to the nation, have been eloquent. The better Bush does, the more confident he gets. For example, it was he who proposed holding a prime-time news conference, at which he smoothly answered questions from a voracious press corps. Even his off-the-cuff remarks have had a genuineness that somehow works. "The guy communicates pretty darn well," says Charles Jones, a presidential scholar at the University of Wisconsin. "The public understands him on a basic level."

Perhaps the best indication of Bush's growing self-assurance was his recent trip to China. Despite the risks of being so far from home during a crisis, he decided to be an example of his own advice that Americans should go on with their lives. He also wanted to eyeball the Chinese and the Russians to make sure they were truly on board his coalition against terrorism. On the campaign trail, Bush was frequently criticized for being naive about foreign affairs. But now the foreign-policy establishment is watching with interest (and some concern) as he forges a warm, new relationship with Russia's Vladimir Putin.

Another area where Bush is getting credit instead of criticism is his choice of advisors. Early on, opponents dismissed his Cabinet as "retreads." Today the steady performances of Defense Secretary Donald Rumsfeld and Secretary of State Colin Powell, in particular, are a comfort to the entire civilized world. To the extent that leadership involves selecting advisors who know their duties better than the leader himself, Bush has shown that he really did earn his Harvard MBA.

Nothing Bush dealt with as governor of Texas comes close to what he's coping with now. ("We're at war," he said the moment the plane hit the second tower.) Critics have long claimed that Vice President Dick Cheney is Bush's puppeteer, manipulating him from behind the scenes. But while Bush delegates most tactical decisions, he is now controlling strategy. Bush, not Cheney, chairs the war council that meets twice daily. Cheney, in fact, has frequently been sequestered elsewhere, fulfilling his one true responsibility: making sure he's available if the President dies or is incapacitated.

In other ways, Bush hasn't changed. "He still likes to invent new words," says White House Chief of Staff Andrew Card. " 'Misunderestimate' is probably going to show up in future dictionaries." Nor has Bush lost his sense of humor. When Ohio Congressman John Boehner came to the Oval Office recently, the President tossed him one of the food packets being distributed in Afghanistan. "Boehner, want some breakfast?" he asked. Bush maintains some less attractive traits as well--such as overpromising. He has always done business with a Texas swagger that says, in effect, "Stop me if you can." It works well when it forces Democrats to compromise closer to his view than theirs. But the notion that the U.S. will rid the world of terrorism--which Bush promised during his speech to Congress--is hyperbolic at best.

Given the nature of the terrorist threat, Bush is forced to play two contradictory and probably irreconcilable roles simultaneously: Commander-in-Chief against an insidious foe, and comforter-in-chief to a rattled nation. Even a President as popular as Bush now is would have a hard time balancing belligerence with reassurance. Nor will he be able to prevent a return to partisanship. The split between congressional Democrats and Republicans is simply too deep. "I don't think the Democrats will let [unity] last," says House Republican leader Dick Armey. "They want to win the House back, and to them, politics is a blood sport." Gephardt also sees division where once there was consensus: "What I had hoped for, and what hasn't happened, is real collaboration."

Over time, as people feel less imperiled by terrorism, the President is sure to fall in the polls (his approval ratings have reached 90%). Iowa Senator Charles Grassley, a Bush supporter, also expects the President's popularity to decline as he campaigns for GOP candidates for Congress next year. "He'll be seen as more partisan than people want to see him in a time of war," says Grassley. But the real test for Bush has nothing to do with partisan politics. In the months ahead, he must cope with a recession, the likelihood of another terrorist attack on U.S. soil, an escalating Middle East conflict, and a fragile international coalition that could crumble if the war extends beyond Afghanistan. So far he has performed admirably. But the better he does, the more we expect of him. From now on, the bar for Bush only gets higher.

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