President Bush and Senator John Kerry sparred over Iraq and other foreign policy issues in the first of their three campaign debates.

They staked out their positions in the first moments of this 90-minute nationally broadcast debate.

Democrat John Kerry said Mr. Bush has misled the country about Iraq. The president - running for a second term as the Republican nominee - accused the senator of shifting his stand for political reasons. "The only thing consistent about my opponent's position is that he has been inconsistent. He changes positions and you cannot change positions in this war on terror if you expect to win. And I expect to win. It is necessary we win," he said.

The senator acknowledged he has made some contradictory statements on Iraq. But he said the president made a colossal error of judgment by diverting attention from the war on terrorism and the hunt for terrorist leader Osama bin Laden. "I made a mistake in how I talk about the war," he said. "The president made a mistake in invading Iraq. Which is worse?"

Senator Kerry said Mr. Bush was not candid with the public about his reasons for invading Iraq or the difficult fight ahead. "You do not take America to war unless you have a plan to win the peace," he said.

The president said progress is being made in Iraq. And he chastised Mr. Kerry for saying more needs to be done to strengthen the coalition fighting with the United States. He said such talk belittles the contributions of the 30 nations currently involved in Iraq. "And I honor their sacrifices. And I do not appreciate it when a candidate for president denigrates the contributions of these brave soldiers," he said. "You cannot lead the world if you do not honor these contributions of those nations. He calls them, 'the coerced and the bribed'."

Both men expressed concern over recent actions taken by Russian leader Vladimir Putin, and the humanitarian crisis in Sudan's Darfur region. They also said the proliferation of weapons of mass destruction is the greatest threat facing the United States.

But they differed on the best way to handle North Korea's nuclear ambitions. Senator Kerry said he wants bilateral talks with Pyongyang, while President Bush spoke against changing the current six-nation approach. "It is a big mistake to do that. You must have China's leverage on [North Korean leader] Kim Jung Il, besides ourselves. And if you enter bilateral talks, they will be happy to walk away from the table. I do not think that will work," he said.

Usually, domestic issues dominate a presidential election campaign in the United States. But since the September 11 2001 attacks, fighting terrorism and national security have become overriding concerns. And so this first presidential debate of this new era took on an added importance, especially for Senator Kerry who is lagging in pre-election polls.

The next debate - which will be held Tuesday - will feature the vice presidential nominees. Senator Kerry and President Bush will meet again on October 8 and 13 - about three weeks before Election Day [November 2].