With his opponent gaining ground in battleground states and his campaign under fire from Democrats for lack of focus, Democratic presidential candidate John F. Kerry yesterday made one of his most vigorous critiques of President Bush's invasion of Iraq, saying it had created a crisis of historic proportions with the "prospect of a war with no end in sight."

"We are fighting a growing insurgency in an ever-widening war zone," Kerry said. "Fallujah, Ramadi, Samarra, even parts of Baghdad are now 'no-go' zones -- breeding grounds for terrorists who are free to plot and launch attacks on our soldiers."

"Saddam Hussein was a brutal dictator who deserves his own special place in hell," said Kerry, who voted in 2002 to authorize the president's use of force in Iraq in the hunt for weapons of mass destruction. "But that was not, in itself, a reason to go to war.

"We have traded a dictator for a chaos that has left America less secure," Kerry said.

The Democratic presidential challenger's speech at New York University, along with his bristling address Thursday to the National Guard Association Conference in Las Vegas, has signaled a clear shift within the Kerry campaign to place the tumultuous situation in Iraq squarely at the center of the 2004 presidential debate.

After fumbling to regain ground in the wake of a Republican convention, which presented Bush as a tested wartime leader and America's trusted protector, the Kerry campaign has tried in recent weeks to zero in on the differences between the Bush administration's rhetoric about Iraq and the reality on the ground, while reminding voters of how the costs of the Iraq invasion and reconstruction have affected their daily lives.

As he has campaigned around the country in recent weeks, Kerry has sharpened his offensive by questioning Bush's credibility, stressing that two key rationales for the invasion of Iraq have been cast in doubt: that there were connections between Iraq and the al-Qaida terror network at the time of the invasion and that Saddam possessed weapons of mass destruction.

In both the New York and Las Vegas speeches, Kerry stressed his new campaign theme that Bush has made the "wrong choices" for the nation, and that he himself could provide a new direction by being a fresh and credible voice on foreign policy.

"The president has made a series of catastrophic decisions from the beginning in Iraq," Kerry said yesterday. "At every fork in the road, he has taken the wrong turn and led us in the wrong direction. He failed to tell the truth about the rationale for going to war, and he failed to tell the truth about the burden this war would impose on our soldiers and our citizens."

The Massachusetts senator's campaign packaged the candidate's speech yesterday with a new ad in battleground states, including Pennsylvania, arguing that the $1 billion that is being spent in Iraq each week is drawing funds away from domestic programs such as health care and education.

While campaigning in New Hampshire yesterday, the president responded by saying his opponent's remarks were a continuation of "his pattern of twisting in the wind."

He seized on Kerry's assertion that the United States had traded a dictator for a less secure America. "He's saying he prefers the stability of a dictatorship to the hope and security of democracy," Bush said. "I couldn't disagree more."

Bush campaign manager Ken Mehlman described Kerry's remarks yesterday as "preaching defeat and suggesting retreat in Iraq" and said the Democrat's critique of the Iraq policy could lead to "a victory for the terrorists."

In arguing that Bush's invasion of Iraq has made the nation less safe, the Kerry team is trying to fight the perception among the majority of potential voters that Bush could better protect Americans from terrorism than Kerry.

Kerry, who has said he would try to extract U.S. troops from Iraq within four years, yesterday laid out a four-point plan for how his agenda would differ from the president's in Iraq.

Kerry said he would convene a summit of world leaders to persuade other nations to take a more active role in creating a secure Iraq and give them more opportunities to bid on reconstruction contracts. Secondly, he advocated for a more streamlined training program for Iraqi security forces that includes training centers for Iraqi policeman by allies outside Iraq.

As a third prong of his plan, Kerry said, he would create a reconstruction program that created more visible improvements in the daily lives of the Iraqi people, and fourth, he would recruit an international force to protect United Nations employees who will be setting the stage for Iraqi elections in January.

But Bush argued yesterday that Kerry's agenda for Iraq was identical to what the administration was already doing.

Polls suggest that Kerry faces considerable obstacles in selling his leadership on the Iraq issue to voters. In a survey of 2,003 adults conducted Sept. 8-13 by the Pew Research Center for People and the Press, 51 percent of respondents said Bush would do the better job of making 'wise decisions' about what to do in Iraq; 39 percent said Kerry would do the better job.

Though nearly 60 percent of voters surveyed in the Pew poll said they didn't think Bush had a clear plan to bring the war in Iraq to a successful conclusion and in spite of the rising casualties in Iraq, 52 percent said the effort was going well or very well.