US vice-presidential candidates Joe Biden and Paul Ryan have clashed sharply in their only debate as polls show a tightening campaign ahead of the election on 6 November.
Thursday night's debate in Kentucky saw feisty exchanges on national security, the economy, taxes and healthcare.
Mr Biden, a Democrat, was aggressive, frequently interrupting his rival as he defended President Barack Obama, while Mr Ryan, a Republican Wisconsin congressman, was comparatively calm in his first debate on the national stage, the BBC reports.
The Democrats are trying to rejuvenate their campaign after what was widely seen as a poor debate performance by Mr Obama in Denver last week. The Republican challenger, former Massachusetts governor and businessman Mitt Romney, has gained steadily in the polls as a result.
The BBC reports Mr Biden was clearly the more knowledgeable candidate on foreign policy, but Congressman Ryan from Wisconsin held his own on domestic issues.
The debate opened with an exchange on Libya, where a US ambassador was killed in September.
Mr Biden defended the Obama administration's handling of the situation, as well as its initially inaccurate characterisation of the incident as a reaction to an anti-Islamic video made in the US.
He attacked Mr Romney, saying the Republican's decision to hold a political press conference the morning after the attack was "not presidential leadership".
"We will find and bring to justice the men who did this. We will get to the bottom of it, and... whatever mistakes were made will not be made again."
In one of many barbs, he said Mr Ryan's criticisms of the administration's handling of the crisis were "a bunch of malarkey. Not a single thing he said is accurate".
Mr Ryan, meanwhile, said the administration had disregarded diplomats' requests for more security in Libya. "If we're hit by terrorists we're going to call it for what it is: a terrorist attack."
The men argued about Iran and the US relationship with Israel, but showed little substantive difference between their tickets' respective policies.
Economy
Mr Biden said the president had inherited a nation teetering on ruin - a result, he said repeatedly, of the Republican policies of George W Bush.
He defended the president's remedies, especially a programme that Mr Romney opposed to save US car manufacturers from bankruptcy.
Mr Biden also unleashed a broadside against Mr Romney's recently publicised comments that the 47% of Americans who pay no federal income tax are dependent on government, consider themselves victims, and should take responsibility for themselves.
"I've never met two guys who are more down on America across the board," he said, referring to Mr Romney and Mr Ryan.
Mr Ryan sought to deflect the attack with a story about Mr Romney's personal generosity and by referring to Mr Biden's own record of verbal blunders.
He acknowledged that Mr Obama had inherited an economy near collapse, but added: "We're going in the wrong direction", noting the continuing high unemployment rate and other grim statistics.
"This is not what a real recovery looks like," Mr Ryan said, promising that Mr Romney's tax plans would add jobs and promote economic growth.
