US Vice President Dick Cheney and Democratic rival John Edwards clashed late Tuesday on Iraq, terrorism, and the economy in their only debate, trading frequent personal attacks 28 days before the November 2 election.
Facing the first question of the televised 90-minute exchange, Cheney said Saddam Hussein had "an established relationship with al Qaeda" and defiantly declared: "What we did in Iraq was exactly the right thing to do."
With millions of Americans watching, Edwards seized on Cheney's claim of links between Saddam and Osama bin Laden's network and charged: "Mr Vice President, you are still not being straight with the American people."
"There is no connection between the attacks of September 11 and Saddam Hussein," said Edwards. "And you've gone around the country suggesting that there is some connection. There is not."
Political analysts agree that vice presidential debates, which date back only to 1976, usually have little impact on the battle for the top job, but Tuesday's debate drew added significance from polls showing a tightening race.
But the absence of a clear, knock-out blow heightened expectations for the second televised face-off on Friday between US President George W. Bush and Democratic rival John Kerry.
ABC News gave Cheney a 43-35 percent edge over Edwards while Fox News had the North Carolina senator on top at 53-46 percent.
Leading US newspapers emphasised the importance of the encounter but shied away from declaring either candidate the outright winner.
The New York Times noted in an editorial that Cheney "seemed tired and angry" while The Washington Post wondered if Edwards "has enough grounding in policy and politics" to perform the job he is running for.
Edwards, 51, hoped to build up Kerry's new momentum following what was widely seen as a victory over Bush in the first of their three televised debates last week.