The political fallout from last night's U.S. presidential debate is being assessed this morning. And an ABC News poll has dubbed Democratic presidential candidate John Kerry the clear winner.

The poll of 531 voters found 45 per cent of viewers favoured Kerry over U.S. President George Bush. Only 36 per cent felt Bush came out on top; 17 per cent declared a tie. 

A CBS poll of 200 voters had similar results, with 43 per cent saying Kerry won, and 28 per cent saying the president won; another 29 per cent said it was a tie.

Throughout the 90-minute debate, the war on terror and the war in Iraq took centre stage. Kerry attacked Bush for making what he called wrong decisions.

"This president has made, I regret to say, a colossal error of judgment. And judgment is what we look for in the president of the United States of America," Kerry told the broadcast from Coral Gables, Florida.

When asked to describe those errors, Kerry smiled at the opportunity before lambasting Bush for "pushing our allies aside" on the road to war in Iraq.

"He also promised America that he would go to war as a last resort. Those words mean something to me, as somebody's who's been in combat."

Furrowing his brow, Bush resisted the Massachusetts Senator's bluster, responding with a firm defence of his foreign policy.

"But the best way to protect this homeland is to stay on the offence," he said. "In the end, we have to be right 100 per cent of the time and the enemy only has to be right once to hurt us."

Bush also turned the verbal attack on Kerry, repeating a theme frequently heard on the campaign trail.

"My opponent says help is on the way. But what kind of message does it send to our troops in harm's way if we say wrong war, wrong place, wrong time? That's not a message a commander in chief gives," Bush said, alluding to his dim view of Kerry's ability to make a decision and stick with it.

The Democratic contender didn't miss a beat before turning the rhetorical barb back on Bush.

"He rushed the war in Iraq without a plan to win the peace.

"Now, that is not the judgment that a president of the United States ought to make. You don't take America to war unless have the plan to win the peace.''

More than 1,000 Americans have been killed in Iraq since the U.S.-led campaign to oust Saddam Hussein was launched in March of last year.

Common ground

Although the war in Iraq dominated the debate, the candidates also aired their differences on Russia, Iran and North Korea. All three are potential threats, Kerry said, charging Bush with allowing their nuclear programs to expand during his first term in office.

Kerry said he would secure Russia in four years and embark on bilateral negotiations with North Korea -- declarations that failed to impress the president.

"I can't tell you how big a mistake I think that is," he said, suggesting that he would rather continue on his current tack.

On Iran, Kerry said the president had been left out of European-led talks. Bush disagreed, saying he hoped to follow the same strategy with Tehran he has been pursuing with Pyongyang.

The pair also found some common ground, agreeing that the killing in Sudan amounts to genocide, for example. Neither candidate said U.S. troops are the answer, suggesting instead the African Union should play a peacemaking role.

Both men offered the same response when asked what they believe poses the gravest threat to U.S. national security.

Although both offered "nuclear proliferation" as their singular response, Kerry said he would lead by example -- stopping development of new 'bunker buster nukes', for example.

Bush, on the other hand, held up his missile shield as key to his anti-nuclear strategy.

Candidate optics

Bush appeared at times impatient or bemused, sometimes smirking as Kerry spoke. The Massachusetts Senator appeared more stoic, frequently bowing his head to scribble notes throughout Bush's remarks.

Watching the debate from Washington, CTV's Alan Fryer said Kerry appeared to have the momentum of the debate on his side. "This was a good night for John Kerry," Fryer said, impressed with his "crisp and concise" remarks.

"And on several occasions he seemed to be able to put the president on the defensive, making Bush appear to have run out of things to say."

Fryer cautioned, however, that it would be premature to declare a clear winner. "I think it's going to take a few days and a couple more polls to learn if the debate will make a major difference."

In recent weeks, the Republican incumbent has edged ahead of Kerry in opinion polls. With a month to go before the Nov. 2 vote, the debate is considered a crucial step in winning the votes of Americans now beginning to think seriously about the election.

As many as 50 million viewers were expected to tune in to see the candidates square off in the state known lately as the site of Bush's disputed election win in 2000.

The second presidential debate will be held Oct. 8 in St. Louis, Missouri. The last forum will take place Oct. 13 in Tempe, Arizona.

Bush and Kerry's respective running mates, Vice President Dick Cheney and Sen. John Edwards, will hold their only face-to-face debate on Oct. 5 in Cleveland, Ohio.