Biden said in a debate Thursday night that "we weren't told" there had been requests for more security at the U.S. Consulate in Benghazi ahead of the terrorist attack one month ago.
A State Department official testified before Congress on Wednesday that she had, in fact, refused requests for more security in Benghazi because the department wanted to train Libyans for the task. Another U.S. official testified he had argued unsuccessfully for more security for weeks.
White House spokesman Jay Carney said that when Biden said "we weren't told," Biden meant President Barack Obama and himself. Carney said such security matters are handled by the State Department.
Asked what the president's reaction was when he heard testimony of State Department officials who had pleaded for more security, Carney said Obama "wants to get the bottom of what happened." He said the president is committed "to make sure that what happened in Benghazi never happens again."
Romney told supporters in swing state Virginia that the White House has more questions to answer about the tragedy.
"The vice president directly contradicted the sworn testimony of State Department officials," Romney said. "He's doubling down on denial. And we need to understand exactly what happened as opposed to just have people brush this aside. 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. And we're going to find out."
Romney said his running mate, Wisconsin Rep. Paul Ryan, gave Americans answers in the 90-minute debate against Biden, not political attacks. And Romney seemed to suggest he didn't think much of Biden's reaction to many of Ryan's answers, with the vice president responding on television's split screens with dismissive chuckles and eye rolls when his rival was speaking.
"There was one person on stage last night who was thoughtful and respectful and steady and poised, the kind of person you'd want to turn to in a crisis," Romney said to cheers. "And that was the next vice president of the United States, Paul Ryan."
Biden, eager to make up for the president's lackluster performance in his first debate with Romney, played the aggressor throughout the debate that came with less than four weeks to go before Election Day. The president gave his running mate a quick thumbs up for delivering with the energy and feeling that he did not.
"His passion for making sure that the economy grows for the middle class came through so I'm really proud of him," Obama said after watching the debate aboard Air Force One on the way home after a day of campaigning in battleground Florida.
Ryan came back at the vice president with harsh talking points, a flurry of statistics and a sharp economic warning: In another Obama term, he said, "Watch out, middle class, the tax bill's coming to you."
Romney, who watched the debate at the end of a campaign day in North Carolina, got on the phone to Ryan immediately afterward to congratulate him. Ann Romney told a rally in the western Michigan town of Hudsonville on Friday that the debate showed why her husband chose Ryan as his running mate.
"What he saw in Paul was a level head, very smart. You can tell, it came through, the kind of character that this man has," Mrs. Romney said.
Ryan declined to engage in any morning-after analysis while stopping for breakfast with his family Friday at Josie's diner in Lexington on his way out of Kentucky. All he would allow is that he felt great about how the debate turned out.
Attention now shifts to the two remaining debates between Obama and Romney: Tuesday's "town hall" style faceoff in Hempstead, N.Y., and a final showdown, over foreign policy, on Oct. 22 in Boca Raton, Fla.
And the campaigns get right back into the thick of it on Friday, looking for ways large and small to shift more voters in their direction in the small number of states whose electoral votes are still up for grabs: Colorado, Florida, Iowa, Ohio, New Hampshire, Nevada, North Carolina, Virginia and Wisconsin.
After his Virginia rally, Romney was linking up with Ryan in Ohio. Biden and wife, Jill, will woo young voters at the University of Wisconsin-La Crosse. Obama will spend a rare day in Washington, preparing for the next two debates and taking campaign contest winners out to eat.
The president has set aside a serious chunk of time for preparation after being faulted for underestimating the importance of his first debate with Romney. He'll be hunkered down in Williamsburg, Va., from Saturday until Tuesday rehearsing with Sen. John Kerry, D-Mass, acting as a proxy for Romney.
The Democrats' monthlong "gotta vote" bus tour will be in Milwaukee on Friday, just in time to rev up supporters for the opening of Wisconsin's early voting season on Monday.
Associated Press writers Nancy Benac and Ben Feller in Washington, Phil Elliott in Louisville, Ky., and John Flesher in Hudsonville, Mich., contributed to this report.