Republican John McCain and Democrat Barack Obama accused one another of glaring errors over Iraq and the economy in their first presidential debate.
Obama, 47, promised to end the "failed" policies of the Bush administration, which he blamed McCain for supporting. McCain, 72, presented himself as a reformer.
The most intense exchanges of the first half of the debate came over Iraq, as Obama claimed credit for opposing the war in the first place, and McCain said he had been instrumental in pushing the successful surge strategy.
"We are winning in Iraq and we'll come home. And we'll come home as we have when we have won other wars and not in defeat," McCain said, warning defeat in Iraq would embolden Al-Qaeda and Iran.
But Obama shot back, saying "six years ago I stood up and opposed this war," condemning McCain for standing with Bush over 2003 US-led invasion to topple dictator Saddam Hussein. "I wish I had been wrong for the sake of the country and they had been right but that's not the case," Obama noted, according to AFP.
And he accused his rival of a catalogue of miscalculations on Iraq. "When the war started you said it was quick and easy, you said we knew where the weapons of mass destruction were. You were wrong.
"You said that we were going to be greeted as liberators. You were wrong. You said that there was no history of violence between Shia and Sunni and you were wrong."
McCain also criticized Obama for having said he would sit down without precondition with Iranian President Mahmoud Ahmadinejad. "So let me get this right, we sit down with Ahmadinejad and he says 'we're going to wipe Israel off the face of the earth' and we say, 'no you're not.' Oh please," McCain said.