By NEDRA PICKLER AND KASIE HUNT, ASSOCIATED PRESS

WASHINGTON — Republican vice presidential nominee Paul Ryan, responding to President Barack Obama's description of the response to a deadly attack in Libya as "not optimal," on Friday accused the White House of stonewalling in the face of mounting questions about its response. Obama promised to provide answers.

"If four Americans get killed, it's not optimal," the president said Thursday during an appearance on "The Daily Show" on Comedy Central. "We're going to fix it."

Obama's GOP rival, Mitt Romney, has been criticizing the administration for saying the attack was a spontaneous mob reaction to an anti-Muslim video on YouTube when they now acknowledge it was a terrorist attack. U.S. officials told The Associated Press that the CIA station chief in Libya reported to Washington within 24 hours of the attack to say there was evidence it was carried out by militants, although it's unclear who received that information right away.

Ryan told "The Charlie Sykes Show" on Milwaukee radio station WTMJ that the White House's story "continues to shift."

"They refuse to answer the basic questions about what happened," Ryan said. "And so his response has been inconsistent, it's been misleading. And more than a month later we still have more questions than answers."

The Wisconsin congressman said he hopes a congressional investigation and Monday night's presidential debate, with its focus on foreign policy, will provide answers.

"That's why you have these investigations in Congress, to find out what exactly happened and why the stonewalling and why blaming (the) YouTube video for two weeks," he said. "The reason we need to get to the bottom of this is so we can prevent something like this from happening again."

Ryan and Romney have been using the death of U.S. Ambassador Chris Stevens and three other Americans on the 11th anniversary of the Sept. 11 attacks to criticize Obama's overall foreign policy record.

"The Benghazi thing would be a tragedy in and of itself if it was an isolated incident," Ryan said on WTMJ. "The problem is it's not simply an isolated incident but a picture of a broader story of the absolute unraveling of the Obama administration's foreign policy. Go around the world and you see policy failure after policy failure, and that is something that they just can't defend."

Obama insisted information was shared with the American people as it came in. The attack is under investigation, Obama said, and "the picture eventually gets filled in."

"What happens, during the course of a presidency, is that the government is a big operation and any given time something screws up," Obama said on "The Daily Show." "And you make sure that you find out what's broken and you fix it."

Asked if the White House had become aware of the CIA cable and when, spokesman Tommy Vietor declined comment "on what, if true, would be an internal and classified CIA cable."

After "The Daily Show" interview, Obama headed to New York's Waldorf Astoria hotel, where he sat one seat away from Romney at the Alfred E. Smith Memorial Foundation Dinner, an annual gala that has drawn political leaders and other notables since the end of World War II. The event was a comedic pause in a contest that has drawn increasingly nasty and close.

On Friday, it was back to campaigning in Florida and Virginia, two of just a handful of states that will decide the Nov. 6 election, now less than three weeks away.

Obama planned a speech at George Mason University in Fairfax, Va., rallying college students in the northern part of the state. Romney was headed to Daytona Beach, Fla., for a rally with Ryan.

Romney made a play for moderate voters in a new ad Friday that featured video of him at the first presidential debate talking about how he would bring both parties together in Washington to help the economy.

While they're both focused on the South, NBC News/Wall Street Journal/Marist polls released Thursday showed Obama retaining his lead over Romney in Iowa and Wisconsin, two Midwestern battlegrounds. Obama's campaign circulated a memo highlighting the president's strength during the early voting period in Ohio, where Romney has largely staked his hopes of winning the White House.

But both were keeping relatively light public schedules before a weekend devoted to preparing for their third and final presidential debate, set for Monday in Boca Raton, Fla. After the event in Virginia, Obama was heading for the Camp David presidential retreat in Maryland to prepare; Romney planned preparations in Delray Beach, Fla.

"The next debate is on foreign policy," Obama told the white-tie audience at Thursday's dinner. "Spoiler alert: We got bin Laden."

Authorizing the raid that killed the terrorist leader was a high point in Obama's term, and polls show voters give him high marks on handling foreign policy. But the attack on the U.S. Consulate in Benghazi, Libya, last month led Romney and Republicans to raise questions about Obama's policy in the Middle East.

Romney spoke first at the dinner, which was to raise $5 million for Catholic charities. Addressing the elegantly dressed crowd, Romney, a millionaire many times over, said: "It's nice to finally relax and wear what Ann and I wear around the house." Of Obama, Romney said: "You have to wonder what he's thinking. So little time, so much to redistribute."

Obama followed, joking that he took a nap during the first debate but also chiding Romney for his wealth.

"Earlier today I went shopping at some stores in Midtown," Obama said. "I understand Gov. Romney went shopping for some stores in Midtown."

He looked to his left, where Romney sat, grinning as his opponent laughed.

___

Hunt reported from New York. Associated Press writer Jim Kuhnhenn in New York contributed to this report.

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  • President Barack Obama and Republican presidential candidate and former Massachusetts Gov. Mitt Romney participate in the second presidential debate at Hofstra University in Hempstead, N.Y., Tuesday, Oct. 16, 2012. (AP Photo/Charles Dharapak)

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  • President Barack Obama, left, speaks to Republican presidential nominee Mitt Romney during the second presidential debate at Hofstra University, Tuesday, Oct. 16, 2012, in Hempstead, N.Y. (AP Photo/Pool-Win McNamee)

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  • President Barack Obama and Republican presidential nominee Mitt Romney speak during the second presidential debate at Hofstra University, Tuesday, Oct. 16, 2012, in Hempstead, N.Y. (AP Photo/David Goldman)

  • HEMPSTEAD, NY - OCTOBER 16: Republican presidential candidate Mitt Romney (L) speaks as U.S. President Barack Obama (R) listens during a town hall style debate at Hofstra University October 16, 2012 in Hempstead, New York. During the second of three presidential debates, the candidates fielded questions from audience members on a wide variety of issues. (Photo by Shannon Stapleton-Pool/Getty Images)

  • US President Barack Obama (R) and Republican presidential candidate Mitt Romney (L) participate in the second presidential debate, the only held in a townhall format, at the David Mack Center at Hofstra University in Hempstead, New York, October 16, 2012, moderated by CNN's Candy Crowley. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • US President Barack Obama (R) and Republican presidential candidate Mitt Romney (L) participate in the second presidential debate, the only held in a townhall format, at the David Mack Center at Hofstra University in Hempstead, New York, October 16, 2012, moderated by CNN's Candy Crowley. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • Republican Presidential nominee Mitt Romney (rear) and US President Barack Obama debate on October 16, 2012 during the second of three presidential debates at Hofstra University in Hempstead, New York. AFP PHOTO / Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)

  • Republican Presidential nominee Mitt Romney (L) and US President Barack Obama debate on October 16, 2012 during the second of three presidential debates at Hofstra University in Hempstead, New York. AFP PHOTO / TIMOTHY A. CLARY (Photo credit should read TIMOTHY A. CLARY/AFP/Getty Images)

  • US President Barack Obama and Republican presidential candidate Mitt Romney both speak at the same time during the second presidential debate October 16, 2012 at the David Mack Center at Hofstra University in Hempstead, New York. AFP PHOTO/Mandel NGAN (Photo credit should read MANDEL NGAN/AFP/Getty Images)

  • US President Barack Obama and Republican Presidential nominee Mitt Romney debate on October 16, 2012 at Hofstra University in Hempstead, New York. Undecided voters asked questions during a town hall format. AFP PHOTO/Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)

  • US President Barack Obama (R) and Republican presidential candidate Mitt Romney (L) participate in the second presidential debate, the only held in a townhall format, at the David Mack Center at Hofstra University in Hempstead, New York, October 16, 2012, moderated by CNN's Candy Crowley. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

  • US President Barack Obama (R) and Republican presidential candidate Mitt Romney (L) participate in the second presidential debate, the only held in a townhall format, at the David Mack Center at Hofstra University in Hempstead, New York, October 16, 2012, moderated by CNN's Candy Crowley. AFP PHOTO / TIMOTHY A. CLARY (Photo credit should read TIMOTHY A. CLARY/AFP/Getty Images)

  • US President Barack Obama (R) and Republican presidential candidate Mitt Romney (L) participate in the second presidential debate, the only held in a townhall format, at the David Mack Center at Hofstra University in Hempstead, New York, October 16, 2012, moderated by CNN's Candy Crowley. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)