Six months before the November election, President Bush has slipped into a politically fragile position that has put his reelection at risk, with the public clearly disaffected by his handling of the two biggest issues facing the country: Iraq and the economy.

Bush continues to run a close race against Sen. John F. Kerry (D-Mass.) in national polls, and his reelection committee has spent prodigiously to put Kerry on the defensive in the opening phase of the campaign, with some success. But other indicators -- presidential approval being the most significant -- suggest Bush is weaker now than at any point in his presidency.

Bush's approval rating in the Gallup poll fell to 46 percent this week -- the lowest in his presidency by that organization's measures. Fifty-one percent said they disapprove -- the first time in his presidency that a bare majority registered disapproval of the way Bush is doing his job. A Pew Research Center survey released Wednesday pegged Bush's approval at 44 percent, with 48 percent disapproving.

In contrast, Bill Clinton and Ronald Reagan, who were reelected easily, had approval ratings in the mid-50s at this point in their reelection campaigns and remained at or above those levels into November. But Bush's father, George H.W. Bush, and Jimmy Carter had fallen to about 40 percent in their approval ratings at this point in their races and, after continuing to fall even further, lost their reelection bids.

Given the volatility of events, the amount of time before Election Day and hurdles Kerry must overcome, Bush has plenty of time to recover. His advisers said that they recognize the weakness in the president's current standing but that he is far more resilient politically than his detractors suggest. They also argue that in this climate, perceptions of Kerry will be just as important as perceptions of the incumbent, and they have poured tens of millions of dollars into television ads attacking Kerry as a politician lacking clear convictions.

Frank Newport of the Gallup Organization pointed out that, in Gallup's surveys, no president since World War II has won reelection after falling below 50 percent approval at this point in an election year. "Looking at it in context, Bush is following the trajectory of the three incumbents who ended up losing rather than the trajectory of the five incumbents who won," he said.

But Newport was quick to add that history may be an uncertain guide, given the volatility of events in Iraq. "There is the potential for this to be a disruptive year that doesn't follow historical patterns," he said.

This president's problems are linked directly to deteriorating perceptions of how he is dealing with Iraq and the economy. A solid majority of Americans now disapprove of his handling of both. As a result, his overall approval rating has declined. But Bush's advisers said his standing in October, not May, is what counts.

Matthew Dowd, senior adviser for the Bush-Cheney campaign, said Bush occupies a unique position compared with former presidents. In past campaigns, Bush's predecessors have either been above 53 percent in approval by the time of the election and been reelected, or have been below 46 percent and been defeated.

"We're in that place where no presidential reelection campaign has ever been," he said. "People say this is a referendum on the president. It's both a referendum on the president but also a referendum on the alternative."

At this point in the race, strategists in both parties said, a president's approval rating may be a clearer and more reliable measure of where the contest stands than head-to-head matchups with the other party's candidate. They say the public first makes a judgment about the incumbent and then looks more seriously at the challenger.

Douglas Sosnik, White House political director during Clinton's 1996 reelection campaign, told the Democratic Leadership Council meeting in Phoenix last week that an incumbent's eventual vote is linked more directly to his approval rating than to any other measure and thus serves as a leading indicator early in the race. Dowd, too, has said repeatedly that the president's eventual vote percentage will track closely with his approval rating.

Sosnik argued that the danger for Bush is that negative perceptions of his performance could harden over the next 90 days, and that even improvements on the ground in Iraq or in the economy will not save him by that point in the campaign.

But Sosnik said yesterday that the extraordinary uncertainty that surrounds the campaign could render historical patterns moot. "Perhaps we are in a new era in politics where the lessons of history no longer apply," he said in an e-mail message. "Based on President Bush's current job approval rating, he had better hope so."

Bush ended 2003 on a sharp spike of support after the capture of Saddam Hussein and hit 64 percent approval in mid-December. But that brief period of rallying behind the president lasted for only a month, and by mid-January his approval rating had fallen to 53 percent in the Gallup poll. He remained in the low-50s throughout the first months of the year, but in the past month, as the violence in Iraq increased and then the scandal over prisoner abuse hit with full force, his standing fell again.

A senior Bush adviser, who asked not to be identified in order to speak openly about the campaign, said: "This is a response to current affairs. When there are difficulties in the world, an incumbent by definition has a short-term hit on his numbers." But he predicted that the closeness of the race only raises the stakes on Kerry to make himself acceptable to voters.

Kerry advisers dispute the GOP view that Bush's approval numbers can easily rebound, arguing that, in a divided nation, he will struggle to get above 50 percent. "I think what you see is a 50 percent president, with that 50 percent being punctured by events," Kerry pollster Mark Mellman said.

He noted that Bush saw his approval ratings soar after the attacks of Sept. 11, 2001, and again when the United States went to war against Iraq. But over time, he said, those numbers receded. "It's very hard to see where the natural line is here because it's almost always sloped as a result of some event," he said. "But I don't think there's anything to suggest there's a natural place for this president to be anything more than 50 percent."

Sour attitudes about the country's direction also are hurting the president, and analysts such as Sosnik said that measure, too, is a leading indicator of the political mood. But Republican pollster Bill McInturff said presidents can win reelection even if a majority of voters say the country is heading in the wrong direction, as they do now. He said he believes the public's mood will brighten if Iraq ceases to dominate the news as it has for the past month.

"Obviously as a campaign we would prefer to be above 50 [percent] than below 50, but you play the cards you're dealt," Dowd said. "Nothing Senator Kerry is doing is affecting our numbers. It's events in the world and how people view the situation in the world or the situation in Iraq."

President Bush is welcomed by students and staff at Parkersburg South High School in Parkersburg, W.Va.