No gloating, President Bush warned his White House staff in November 2002. It was an order he strained to follow himself.

Flush with his success at leading Republicans to victory in congressional midterm elections, Bush claimed the results as a mandate for his policies on terrorism, Iraq and tax cuts, and for his brand of trust-my-gut conservatism. "I think the way to look at this election is to say that people want something done," he told reporters. To skeptics at home and abroad, he declared: "I don't spend a lot of time taking polls . . . to tell me what I think is the right way to act; I just got to know how I feel."

As Bush heads to the Republican National Convention in New York this week, the man who stood astride the political world at that news conference in 2002 is a distinctly more life-size figure. With the election just 65 days away, there is a puzzle: How did a leader who was so formidable become so vulnerable?

In small ways, the answer is an accumulation of miscalculations and missed opportunities that have marred the president's political operation this year, in the view of some Republicans inside that operation and others beyond it. In a large way, however, Bush's predicament is less a reversal of his 2002 success than a natural progression of it -- the consequence of two confrontations he sought that autumn.

To the dismay of Democrats, who suspected he was manipulating national security for political advantage, he invited the electorate two years ago to judge him over the then-looming confrontation with Iraq. To the delight of Democrats, it is precisely such judgments that polls say are shadowing his reelection campaign.

By the same token, his decision to confront Democrats directly and immerse himself in partisan electioneering ensured that he would face reelection with little of the rally-behind-the-leader sentiment that flowed to him after the Sept. 11, 2001, attacks.

To the contrary, Bush's decisions and political style have virtually eliminated the political center -- sending all but a small percentage of Americans into fevered pro- and anti- camps -- and dictated a general election strategy organized around exciting core supporters and increasing turnout. This approach upends conventional reelection strategy, which holds that a president should mostly finish his base-tending the year before voting, and spend the general election softening his rhetoric and showering blandishments on independent voters in the ideological middle.

Matthew Dowd, the Bush-Cheney campaign's senior strategist, said the conventional strategy is obsolete in an election dominated by national security: "The same thing that appeals to our partisans appeals to those folks in the middle, which is: What are you going to do about terror?"

Drawing a contrast with President Bill Clinton, Dowd added that both groups admire a president willing to take controversial actions to meet problems, rather than expending political capital on small-but-popular initiatives: "This is a president who decided to play big ball instead of small ball."

There are indications that, in the homestretch, Bush is planning to return to the milder brand of "compassionate conservatism" on which he ran in 2000. This week's GOP convention will feature such speakers as California Gov. Arnold Schwarzenegger and former New York mayor Rudolph W. Giuliani, who hold clear appeal to moderates, even though they have views on abortion and other social topics that are anathema to the party's conservative base. Democratic strategists say they are surprised that Bush is making this pivot so late, and only this week planning to lay out more details of a proposed second-term agenda.

Without question, it is real-world facts -- events in Iraq, the economy at home -- that are shaping Bush's reelection prospects more than any decision about strategy, in the view of campaign operatives with the president and the Democratic nominee, Sen. John F. Kerry (Mass.).

Even so, a variety of critical Democrats and anxious Republicans outside Bush's campaign believe that the long and mostly downward arc of Bush's political strength over the past year is also the result of some specific misjudgments. Two stand out as most important:

* The enactment of a prescription drug benefit under Medicare in December. The expectation was that by delivering on this promise, which is the most expensive expansion of government social benefits in 40 years, Bush would take away an issue that historically had belonged to Democrats. As it happened, by passing a bill with mostly GOP support Bush did not reap much political gain. Polls show voters still strongly trust Democrats and Kerry more than Bush to protect senior citizens' health care, and many are wary of a benefit that is more complicated and slower to arrive than they wanted.

* The missed opportunity of the State of the Union address in January. Bush spoke to a large national television audience, but polls showed little movement upward in his support. Critics said that in content and tone, much of his rhetoric seemed aimed at existing supporters of his Iraq and tax-cut policies rather than presenting new arguments to doubters. He foreshadowed his support for a constitutional amendment to block gay marriage, which polls say is the most important issue for social conservatives, at the risk of alienating more tolerant independents who think the issue should be decided by states.

These large events were reinforced by several smaller ones, including what even some Bush political aides acknowledge were middling performances in a high-profile "Meet the Press" interview on NBC last winter and a news conference in the spring in which he professed himself stumped when asked whether he could think of any mistakes he had made.

In its own way, that answer was of a piece with the values Bush has followed at every major juncture of his presidency. It is a brand of politics that believes the assertion of power can create the reality of power -- and that it is preferable to act boldly and make other politicians accommodate Bush's agenda rather than try to accommodate their doubts. Bush did not offer coalition government after winning the contested 2000 election with a minority of the vote, nor did he offer to split the difference when Democrats complained that his tax cuts were too large. Instead, he corralled Republicans and a handful of Democrats and enacted the tax cuts into law.

A top official from a former Republican White House said Bush's governing operation created critical problems for his political arm by deciding to "divide and conquer rather than unite and win." This official, who refused to be identified because he works with Bush's inner circle, said that largely because of Vice President Cheney's influence, the White House adopted a confrontational style with Capitol Hill and with the Democratic Party that is endangering Bush's chance of reelection. "There's nobody over there saying 'No,' " the official said. "It's all the same Kool-Aid. Instead of the art of governing, it's been, 'Are you for me or against me?' "

Steven Schier, a Carleton College political scientist, has edited a book on Bush's political style called "High Risk and Big Ambition." In pursuit of large goals, Schier believes, Bush and his political team are willing to take "audacious risks" with voters in the middle so long as the GOP base is secure; 2002 showed the rewards of this style, while 2004 has so far highlighted the perils.

"When you take risks, if your premises are wrong, you pay a price," said Schier, who noted that Bush might well be coasting to victory had he been proved right that Iraq had weapons of mass destruction or that tax cuts would have an unambiguous stimulative effect on the economy. As it is, Schier said, Bush has spent the year stroking his partisan base and pursuing an electoral strategy that amounts to "reaching the top of a low ceiling."

The Clinton Comparison

In 2000, Bush campaigned expressly inviting a comparison of his leadership style and Clinton's. "They have not led; we will," he declared at his first nominating convention. What has been striking about the past two years is the extent to which Bush has been a mirror opposite of Clinton.

The comparison worked to his advantage in the fall of 2002. Clinton's first midterm elections resulted in a massive repudiation of his party and majority control that Republicans have yet to surrender. The GOP gains after two years of Bush contradicted long history dictating that a new president's party loses seats in midterm elections.

Clinton's humiliation forced him to transform his strategy for reelection. He adapted a governing style in which he cast himself as unconcerned with partisan politics and relentlessly embraced policy positions that had been extensively polled and proved popular with large majorities. After the State of the Union address in 1996, when Clinton angered liberals in his party but captured the center with his declaration that "the era of big government is over," he never trailed in the race for reelection. By August, after Republican Robert J. Dole's convention but before his own -- exactly the point where Bush is now -- Clinton was leading by 10 points in the polls. Bush started the month a couple of points behind Kerry but has nudged slightly ahead in several recent polls.

In contrast to Clinton's "near-death experience," Bush's experience apparently has emboldened him to believe that he can win by playing down independents and "making Republicans come out of the woodwork," said Bruce Reed, a former Clinton administration official. The Clinton comparison is revealing of Bush's election strategy in other ways. Clinton's brand of campaigning involved regular policy pronouncements and proposals, sometimes several a week. Some, such as cell phones for neighborhood watch groups, were criticized as piddling, but collectively they presented a vision of a smaller-but-still-activist government that proved popular with voters.

The president is focused on large questions of national security and the changing economy, and has no interest in such minutiae, even if popular, said Ken Mehlman, Bush's campaign manager.

But critics say Bush has not filled out his policy agenda for a second term in ways big or small. White House communications director Dan Bartlett said the president made a decision to save many details about his vision for his acceptance speech.

Mark Penn, a Clinton pollster, believes the shortcomings of Bush's political strategy on both domestic policy and Iraq were on vivid display in the State of the Union address. While no rhetorical formulation could offset bad news, such as the Abu Ghraib prison scandal or mounting U.S. casualties in Iraq, the political costs of these would have been lessened if Bush had presented "more of a flow of information and an explanation to state the case," Penn said. Bush has later made such acknowledgments, but his initial posture of refusing to admit error or surprise apparently caused many people to stop listening to him, Penn said.

Keeping Up Appearances

There were few indications that Bush hit panic buttons last January. This was the same month that one of the White House's 2003 assumptions about the campaign -- the president would be running against the antiwar Howard Dean -- was overturned by Kerry's comeback success in Iowa and New Hampshire. Even then, the assumption was that Bush's then-formidable financial lead could be used to fund advertising that would leave Kerry irrecoverably behind in polls by the time of his convention. This did not happen, although Bush aides say they are pleased at polls showing that ads depicting Kerry as weak-willed and a flip-flopper have influenced public opinion.

The public posture of unyielding optimism about Bush's prospects and insistence that his strategy has worked creates a dissonance. Top Bush operatives such as Mehlman say they have been surprised that Kerry has not offered more policy substance to date, and other Bush aides are more blunt in bad-mouthing the Democrat as a weak candidate. In the next breath, they say the campaign is happy with the president's posture -- even though he is running even, with job approval ratings under 50 percent in most polls.

Surely, though, it would have come as a rude surprise if Bush strategists had been told a year ago that two months before the election the president would be running even with a man they regard as a clumsy opponent. In fact, the numbers illuminate a steady decline. Bush's job approval in a Washington Post-ABC News poll this month was 47 percent, 11 points lower than a year ago. Even his core asset -- the public's confidence in how he is handling terrorism -- has dropped more than 20 points from the spring of 2003 to this summer, and stands in the mid-50s.

Some White House officials acknowledge they have not had a major success since the capture of Saddam Hussein in December, which provided a fleeting bump in polls. Some of these officials have begun what is the rare process of second-guessing themselves. For instance, some of Bush's senior aides believe they would be better off if they had preserved Medicare prescription drugs to use as a campaign issue.

But Dowd said no strategy was going to prevent the election from being a narrowly fought and highly polarized contest. "The dominant parties occupy 90 to 92 percent of the landscape. There are very few people that swing in the middle anymore," he said. "We're playing within the 45- or 47-yard lines, so nobody's going to break away in this thing." Bartlett predicted that Bush's aggressive posture will pay dividends this fall, as even people who disagree with him on particulars appreciate that "there's no ambiguity where he stands." Paraphrasing a hypothetical voter, Bartlett said, "Do I agree with everything Bush is doing? No. But on the big things, I feel pretty good about him, or reassured about him. If things go wrong again, I feel good about him being there."

Polls show President Bush reaped little political gain by enacting the Medicare prescription benefit last December, left, without Democratic backing and playing to supporters in his 2004 State of the Union address.