Democratic presidential candidate John Kerry said Tuesday that President Bush has no credibility with world leaders because of his decision to invade Iraq. For his part, the president defended his Iraq policy in a speech before the United Nations General Assembly in New York.

In a rare news conference, Senator Kerry told reporters in Florida that President Bush "failed to level" with world leaders on the difficulties in Iraq during the president's address to the United Nations General Assembly.

"Iraq is in crisis and the president needs to live in the world of reality, not in a world of fantasy spin," said Mr. Kerry. "After lecturing them instead of leading them to understand how we are all together with a stake in the outcome of Iraq, I believe the president missed an opportunity of enormous importance for our nation and for the world. He does not have the credibility to lead the world and he did not and will not offer the leadership in order to do what we need to do in order to protect our troops, be successful and win the war on terror in an effective way."

Senator Kerry said the administration's management of Iraq has been, in his words, "arrogant, lacking in candor and incompetent" and called for a change in policy. On Monday, Senator Kerry outlined a series of steps he would take in Iraq if elected that include reaching out for more international help and improved training for Iraqi security forces.

Earlier in New York, President Bush used his annual address to the United Nations General Assembly to appeal for more international support for the new governments in Afghanistan and Iraq amid fears that terrorists will attempt to disrupt upcoming elections in both countries.

"?But these difficulties will not shake our conviction that the future of Afghanistan and Iraq is a future of liberty," said Mr. Bush. "The proper response to difficulty is not to retreat. It is to prevail. The advance of freedom always carries a cost."

Meanwhile, a new poll released here in Washington gives the president a four-point lead among likely voters. The bipartisan Battleground Poll, sponsored by George Washington University, found Mr. Bush leading Senator Kerry by 49 to 45 percent.

Republican strategist Ed Goeas says the president has solidified his image as a decisive leader in the wake of the Republican convention.

"As a result of that convention, Bush now has the largest lead he has had over Kerry this entire campaign on who is a strong leader," said Mr. Goeas. "He [Bush] has a 21-point lead [on this issue]."

However, Democratic strategist Celinda Lake predicts that the president may still have trouble winning over undecided voters.

"The few undecided voters who exist out there are remarkably negative in their view," she said. "They solidly believe the country is going in the wrong direction."

The Battleground Poll was conducted last week based on interviews with 1000 voters nationwide. It has a margin of error of plus or minus three percent. Several other recent polls have also given the president a lead over Senator Kerry.