On Friday, the White House said that the vice president in the debate was referring only to his and the president's direct knowledge of such a request for staffing.
''He was speaking directly for himself and the president," said White House spokesman Jay Carney.
Romney has portrayed the attack as a sign of Obama's weakness abroad and the unraveling of the country's foreign policy. On the stump in Richmond, Va., Romney alluded to the mounting questions, saying Biden was "doubling down on denial."
''When the vice president of the United States directly contradicts the testimony -- sworn testimony -- of State Department officials, American citizens have a right to know just what's going on," Romney said. "And we're going to find out. And this is a time for us to make sure we do find out."
Obama campaign spokeswoman Lis Smith quickly responded: "As Secretary 1/8Hillary3/8 Clinton said today, the president and his administration have been focused on getting the facts about what happened in Libya, finding the terrorists responsible, and bringing them to justice. But Mitt Romney has repeatedly rushed to launch political attacks without knowing all the facts."
Romney's stronger performance has boosted the Republican in polls, striking concern among Obama supporters who hope for a stronger showing on Tuesday debate, or risk further erosion, particularly in toss-up states.
During Thursday's debate, Biden scoffed at Ryan's "lecture on embassy security," suggesting that the federal budget Ryan authored as the chair of the House Budget Committee threatens to weaken protection of diplomatic facilities worldwide.
''The congressman here cut embassy security in his budget by $300 million below what we asked for," Biden said.
The vice president's assertion assumes that wholesale cuts in the Ryan budget would be spread uniformly across a series of programs.