At last week's Republican convention, President Bush and Vice President Cheney repeatedly linked the Sept. 11, 2001, attacks and the war in Iraq, largely abandoning the rationale offered when the Bush administration invaded the Persian Gulf country.

Announcing the invasion on March 19, 2003, Bush said in a nationwide televised address that the United States "will not live at the mercy of an outlaw regime that threatens the peace with weapons of mass murder." Two days earlier, Bush had asserted in another address to the nation, "Intelligence gathered by this and other governments leaves no doubt that the Iraq regime continues to possess and conceal some of the most lethal weapons ever devised."

But no such weapons were found after the invasion, and the subject was only fleetingly mentioned from the podium in Madison Square Garden. Instead, the war on Iraq was presented as a part of a seamless thread that stemmed directly from the terrorism of the Sept. 11 attacks. "We have fought the terrorists across the earth -- not for pride, not for power, but because the lives of our citizens are at stake," Bush said, before listing Iraq along with the struggle against terrorist groups in Afghanistan, Pakistan and Saudi Arabia.

Ever since the failure to find weapons of mass destruction in Iraq, the Bush administration has searched for explanations for how to defend the war, such as the need to bring freedom to the Middle East and to end the brutal nature of Iraqi president Saddam Hussein's government. With Bush's convention speech, the administration laid out its most sweeping case to date -- and campaign officials are betting voters will buy this retooled version of the need to go to war.

"The president was very definitive about winning the war against terrorism, and the role that the battleground in Iraq plays in that war," campaign spokesman Terry Holt said. "The policy of preemption has put us in an offensive posture against the terrorists," he said, referring to Bush's pledge in 2002 to attack potential enemies first.

Polls show the grinding and uncertain conflict in Iraq has deeply troubled many voters about Bush's judgment, and analysts said the rhetorical link to the Sept. 11 attacks was intended to remind voters of Bush's greatest moment as president -- his take-charge attitude after the terrorist attacks. From the start of his speech, Bush invoked Sept. 11, and he even quoted an active-duty soldier writing about the "terrorist enemies we are facing in Iraq."

It is a familiar strategy. Bush and particularly Cheney have long suggested links between Hussein and terrorist groups, even al Qaeda. But investigations after the war, such as the inquiry by the bipartisan Sept. 11 commission, have largely disproved the alleged connections. Yet in their convention speeches, the president and the vice president linked Sept. 11 and Iraq even more tightly than before.

"In a campaign that has reached around the world, we have captured or killed hundreds of al Qaeda," Cheney said, in quick succession mentioning the wars in Afghanistan and Iraq. "In Iraq," he said, "we dealt with a gathering threat and removed the regime of Saddam Hussein."

Democratic presidential nominee John F. Kerry devoted only six sentences to Iraq policy in his 45-minute acceptance speech in July, though he has strongly criticized the Bush administration's competence in handling the war, principally its failure to enlist other nations to its cause in Iraq.

Last month, Kerry said that even if he had known in 2002 what is known now about the failure to find weapons of mass destruction, he still would have voted to give Bush the authority to go to war. But he qualified his comments by criticizing Bush for going to war without more international support and for rushing to combat without a plan to win the peace.

In a barrage of attacks last month, Bush and Cheney ignored Kerry's qualifiers and accused him of flip-flopping.

Kathleen Hall Jamieson, director of the Annenberg Public Policy Center, said Kerry's statement last month opened the door for Republicans to avoid talking about the failure to find weapons. "It makes no sense [to bring it up] if the other side has already conceded that case," she said.

Kerry's foreign policy advisers, however, said the linking of the Sept. 11 attacks and the Iraq war is a huge stretch, and Bush should not avoid responsibility for taking the country to war for reasons that turned out to be wrong.

"I think the administration is testing the theory that you can fool all of the people some of time," said Richard C. Holbrooke, a senior foreign policy adviser. He said that the assertion that Hussein possessed banned weapons allowed Bush to claim he needed to go to war immediately, even when it was opposed by many countries. "Once you remove the rationale for war, you no longer have the urgency that justified it," Holbrooke said, adding that "every politician knows that when you don't have a good case, you change the subject."

Rand Beers, the Kerry campaign's national security coordinator, said, "It is part of the big lie, or the big misrepresentation, to make the connection, because if it is perceived there is a connection, it takes away from the failure to find weapons of mass destruction."

Other convention speakers also linked Iraq to the war on terrorism. "In any plan to destroy global terrorism, Saddam Hussein needed to be removed," former New York mayor Rudolph W. Giuliani said, dispensing with the failure to find banned weapons by declaring that Hussein "was himself a weapon of mass destruction."

The administration tried to win the support of the U.N. Security Council for its attack on Iraq but failed, and its decision to go to war without U.N. approval ruptured relations with many key allies, including France, Germany, Canada and Mexico.

In his speech, Bush glossed over such diplomatic drama, in effect airbrushing it out of the picture. He referred to an earlier U.N. resolution, which had brought U.N. weapons inspectors back into Iraq, and then said that "we gave Saddam Hussein another, a final chance, to meet his responsibilities."

Jamieson said she was struck by the speechwriter's effort to make the "we" appear as though it referred to the United Nations, suggesting Bush had widespread diplomatic backing for the attack. "It was very clearly worded so that there would be ambiguity," she said.

While Bush reached back to Sept. 11 to defend the war against Iraq, he gave few clues about how he would end combat and bring home the nearly 140,000 U.S. service members there. "Our mission in Afghanistan and Iraq is clear: We will help new leaders to train their armies and move toward elections, and get on the path of stability and democracy as quickly as possible," Bush said. "And then our troops will return home with the honor they have earned."

Holbrooke dismissed the president's statement as a "wish without a strategy attached to it. They have no strategy -- not a success strategy or an exit strategy."

Kerry has said he can win more international support to secure Iraq, saying in an interview last month that "within a year from now, we could significantly reduce American forces in Iraq." Yet he has declined to offer details.

Holt said that "Kerry made a horrible mistake" by offering a timetable for bringing down the number of U.S. military personnel, saying that will embolden insurgents. Bush's statement represented "a recipe for peace," Holt said. "We need to demonstrate the determination and patience to get it done."

At the GOP convention, President Bush rallied the crowd by saying, "We have fought the terrorists across the earth."Vice President Cheney, speaking the night before Bush, mentioned al Qaeda and quickly drew a connection to Saddam Hussein.