The Bush administration's strategy in Iraq has been critised by US senators as General David Petraeus, the top US military commander in the country, appeared before the senate for his second congressional hearing in two days.
"It's time to turn the corner," Biden said. "We should stop the surge and start bringing our troops home."
Petraeus repeated his belief that the "surge" was going well.
Rob Reynolds, Al Jazeera's correspondent in Washington, said although the testimony was the same, the exchanges with senators was "far sharper".
'Narrow margins'
Senator Richard Lugar, the most senior Republican on the senate foreign relations committee, told the hearing: "Some type of success in Iraq is possible, but as policy makers, we should acknowledge that we are facing extraordinarily narrow margins for achieving our goals."
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Lugar has called for a sizable withdrawal of US troops in the coming months, a plan that runs counter to the recommendation by the Petraeus that the US withdraw the 30,000 extra troops deployed this year, but maintain at least 130,000 troops.Petraeus has said the "surge" of troops was aimed at bringing security that would provide a platform of political progress and reconciliation in Iraq.
Several protesters who heckled the hearing were ejected from the chamber in a repeat of similar scenes the day before.
'Broken promises'
The Iraqi government on Monday welcomed Petraeus' report and
Mowaffaq al-Rubaie, Iraq's national security adviser, said that in the near future he expected "our need will be diminished for the multinational forces to conduct direct combat operations".
Special report But the government of the Iraqi prime minister, Nouri al-Maliki, has come under criticism for failing to make progress on any benchmarks set by the US.Petraeus has previously stressed that his testimony was his own and had not been shown to anyone in the White House or Pentagon amid suggestions from Democrats prior to the hearing that it would be politcised.
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But in an editorial on Tuesday, the New York Times described the general's testimony as "another of the broken promises and false claims we have heard from Mr Bush".