In a testy confrontation on Friday that saw Kerry questioning Bush's judgment and the president accusing Kerry of crumbling under political pressure, the two rivals in the race for the White House repeatedly accused each other of misleading Americans.

"The world is more dangerous today because the president didn’t make the right judgment," Kerry said at the debate at Washington University, adding Bush "took his eye off the ball" in shifting his focus to Iraq while Iran and North Korea developed nuclear programmes.

Unrepentant Bush

Bush defended his decision to go to war and aggressively attacked Kerry's records, saying the senator's willingness to shift in the political winds made him an unsuitable leader.

Kerry accused Bush of rushing
into the Iraq war

"I don’t see how you can lead this country in a time of war, in a time of uncertainty, if you change your mind because of politics," Bush said.

Kerry denied shifting positions and said Bush was running a campaign of "mass deception".

"Let me tell you straight up: I have never changed my mind about Iraq. I do believe Saddam Hussein was a threat. I always believed he was a threat," he said.

Kerry charge

"This president rushed to war, pulled our allies aside, and Iran now is more dangerous, and so is North Korea, with nuclear weapons. He took his eye off the ball, off of Usama bin Ladin," Kerry said.

An angry Bush at one point cut off moderator Charles Gibson to upbraid Kerry for criticising the size of the coalition backing the United States in Iraq, saying it denigrated allies like Britain and Poland.

Kerry responded that if all the citizens of the state of Missouri were a military force in Iraq, they would be the third largest block behind the United States and Britain.

"That’s not a grand coalition," he said.

Keen debate

The debate was conducted in a town hall format, where the candidates perched on stools or moved around the stage to answer questions from an audience of undecided voters.

Bush brushed off the report earlier this week from weapons inspector Charles Duelfer, which found that Iraqi leader Saddam Hussein had not rebuilt his weapons of mass destruction programme after the 1991 Gulf War.

President Bush maintained he was
right in invading Iraq

"Saddam Hussein was a threat because he could have given weapons of mass destruction to terrorist enemies. Sanctions were not working. The United Nations was not effective at removing Saddam Hussein," he said.

Kerry said the goal of sanctions was not to remove Saddam, but to remove the weapons of mass destruction. Turning to Bush, he said: "Mr President, just yesterday the Duelfer report told you and the whole world they worked. He didn’t have weapons of mass destruction, Mr President. That was the objective".

Kerry cited a lackluster jobs report as proof the economy was still weak under Bush. Bush said the economy was adding more jobs since it bottomed out last year and warned the Kerry would halt the economic recovery by raising taxes on middle class Americans.

"He is going to tax everybody here," Bush said, describing Kerry as the Senate's most liberal member.