WASHINGTON – For the first time, Senator Kerry accused President Bush and Vice President Cheney yesterday of deliberately manipulating intelligence to provide a rationale for the invasion of Iraq.

He said the evidence of weapons of mass destruction that the administration offered to the nation as a reason for the war was overblown and “purposefully used to shift the focus from Al Qaeda and Osama bin Laden to Iraq and Saddam Hussein.”

On the eve of a debate with Mr. Kerry that Mr. Bush may need to win if he’s to halt a gathering threat from his Democratic rival, the president, too, maintained his sharp words for the Massachusetts senator on Iraq.

Mr. Kerry wasn’t scheduled to enter the campaign fray yesterday but took time out from prepping for tonight’s debate at St. Louis to respond to the final report of the American weapons inspector in Iraq, Charles Duelfer, which concluded that Saddam Hussein had no stockpiles of banned weapons.

The Democrat nominee said the Duelfer report “provided definitive evidence as to why George Bush should not be re-elected president of the United States.” Mr. Kerry accused Messrs. Bush and Cheney of failing to appreciate the severity of the problems in post-Hussein Iraq, saying they “may well be the last two people on the planet who won’t face the truth.”

Campaigning in Wisconsin, Mr. Bush countered that his opponent was continuing with “his pattern of overheated rhetoric.”

“He now claims that I somehow misled America about weapons, when he himself cited the same intelligence about Saddam’s weapons as the reason he voted to go to war,” Mr. Bush said. “Two years ago this Saturday, back when he was for the war, my opponent said on the floor of the United States Senate – and I quote: ‘Saddam Hussein, sitting in Baghdad with an arsenal of weapons of mass destruction, is a different matter. In the wake of September 11, who among us can say with any certainty to anybody that those weapons might not be used against our troops or against allies in the region?’

“Now today,” the president said, “my opponent tries to say that I made up reasons to go to war. Just who is the one trying to mislead the American people?”

Earlier, Mr. Bush defended his decision to invade Iraq, saying the Duelfer report demonstrates that Mr. Hussein was “systematically gaming the system” of sanctions. The president also said the deposed dictator had the “intent of restarting his weapons program when the world looked away.”

Mr. Bush conceded that the pre-war American and allied intelligence was “wrong” and that this required an explanation. But he insisted he was “right to take action” and “America is safer today with Saddam Hussein in prison.”

The president said of the Iraqi: “He retained the knowledge, the materials, the means, and the intent to produce weapons of mass destruction, and he could have passed that knowledge on to our terrorist enemies. Saddam Hussein was a unique threat, a sworn enemy of our country, a state sponsor of terror operating in the world’s most volatile region.”

Mr. Bush received support for his position from overseas allies. Prime Minister Howard of Australia – who is also locked in a neck-and-neck election race – and Prime Minister Blair of Britain made arguments like Mr. Bush’s and said they had no regrets about joining the U.S.-led coalition that ousted Mr. Hussein.

During a campaign stop in Florida, Mr. Cheney argued the report shows that “delay, defer, wait wasn’t an option.”

While the president was placed more on the defensive yesterday because of the Duelfer report, campaign officials say he intends to take the fight to Mr. Kerry in St. Louis, in much the same way that Mr. Cheney did with Senator Edwards in their face-off on Tuesday.

Mr. Bush is likely to cite improved job figures to be released this morning as evidence that his economic policies are paying off, officials of his campaign said.

Determined to erase an unsteady performance last week in the first debate, Mr. Bush is expected to argue that two jobs reports due out today from the Labor Department demonstrate the jobs market is strengthening.

The Labor Department’s report for September is expected to show that 150,000 jobs were added to the economy. More significant, though, will be the department’s revised estimate of the number of payroll jobs created in the period to March 2004 from March 2003. The estimate could add as many as 400,000 jobs to Mr. Bush’s record.

Yesterday, the Labor Department reported that new claims for jobless benefits fell last week to the lowest level since the beginning of September.

Mr. Bush is likely to employ some of the attack lines he used midweek in his retooled stump speech. The thrust of his argument has been that Mr. Kerry is too inconsistent to be trusted with the nation’s defense and is wrong about the economy. But he also may try to put the onus on Mr. Kerry to explain a Senate record of opposing tax cuts and strong defense policies.

“The debate is an opportunity for Senator Kerry to defend a 30-year record of being wrong on defense, which even John Edwards was unable to defend” the campaign manager for Bush-Cheney ’04, Ken Mehlman, said. “It’s an opportunity for him to explain what he meant by the ‘global test’ and how America would pass it under his leadership, and why an American commander in chief should have to pass a ‘global test’ before defending our country. It’s an opportunity for him to explain how a record of 11 different positions on the war in Iraq can be called ‘consistent.'”

In a conference call with reporters, Bush campaign advisers said they think the race has for now “settled into a two-point advantage” for Mr. Bush, but they said the gap will widen again when the debate series ends Wednesday in Arizona.

“We said when this race began that we thought it would ultimately be a 3-or 4-point race at most,” said the chief strategist, Matthew Dowd. “We expect it to finish up that way through the course of these debates and on to Election Day.”

Opinion polls published yesterday confirmed that the race has tightened since the first presidential debate. According to a Washington Post poll, Mr. Kerry has gained ground on Mr. Bush, with the president leading his Democrat opponent by 49% to 47%among those most likely to vote.

New state polls also suggest the fight is close, with the president ahead of Mr. Kerry in Florida but trailing in another key battleground state, Pennsylvania. The Keystone Poll had Mr. Kerry at 49% to Mr. Bush’s 43% in a sample of likely voters. Mr. Bush has campaigned repeatedly in Pennsylvania, which the Democratic nominee four years ago, Vice President Gore, carried by more than 200,000 votes.

In Florida, another state regarded as must-win, a Mason-Dixon poll found Mr. Bush leading Mr. Kerry, 48% to 44%. But a Quinnipiac University poll gave the president a wider lead there, 51% to 44%.

Both campaigns say the town-hall format of tonight’s debate, less rigid and formal than last week’s format, favors their candidate. The candidates will be permitted to walk around, and the rules of engagement are more loose.

Mr. Kerry has done dozens of town hall meetings during the election season, say his advisers. But a senior Kerry adviser, Michael McCurry, acknowledged the St. Louis format “fits the president’s genial style” – although he said Mr. Bush “needs a home run because he needs to get back in the ball game.”

“The president will be ready,” Mr. Mehlman said. “He’s energized by going out on the road, he loves talking to the American people.”

Democratic strategists said Mr. Kerry will use the debate to firm up the party’s black vote. Polling data from the Pew Research Center suggested that Mr. Kerry’s standing among black voters had fallen off in August by 10 percentage points, to 73%.

In response the Kerry campaign dispatched black members of Congress to battleground states in the Midwest and Mr. Kerry spoke Monday at a meeting of 300 black religious leaders.