President Barack Obama talks with Jon Stewar during a taping of his appearance on "The Daily Show with John Stewart" on Thursday in New York.

By NEDRA PICKLER and JIM KUHNHENN

Associated Press

NEW YORK - President Barack Obama on Thursday rejected criticism that his administration has offered a confused response to the attack on the U.S. Consulate in Libya, an accusation made repeatedly by Republican challenger Mitt Romney in their campaign for the White House. Of any breakdown that might have led to the killing of four Americans, Obama declared: "We're going to fix it."

On a campaign day where the politics of comedy were to flavor the presidential race, Comedy Central host Jon Stewart got serious in pressing Obama over the government's changing explanation about the Sept. 11 attacks in Benghazi. When Stewart suggested that even Obama would concede his administration's coordination and communication had not been "optimal," Obama said: "If four Americans get killed, it's not optimal. We're going to fix it. All of it."

Romney has pointedly questioned Obama's handling of the matter and his honesty about it to voters. Those accusations led to the fiercest conflict of the presidential debate on Tuesday and will surely come to the fore again on Monday in the campaign's final debate.

Appearing in a taping of Comedy Central's "The Daily Show," 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."

The exchange came on a day when Vice President Joe Biden compared the policies of Romney's running mate, Rep. Paul Ryan of Wisconsin, to a gun pointed at Americans, and after Romney's son said he was tempted to "take a swing" at Obama when the Democrat questions the GOP candidate's honesty.

Ryan, speaking at a campaign stop in Ocala, Fla., before Biden delivered his comments, accused Obama of sending a divisive message.

"He's basically trying to disqualify his opponent with a sea of negativity," Ryan said. "He's trying to divide this country, pitting people against each other. He's trying to win this election by default. You know what? We're not going to let him get away with that."

The sharpness of the barbs is a reflection of just how tight the race is 19 days out. Hard campaign decisions are being made, state by state.

Romney aides said Thursday that no staff had been dispatched to Michigan or Pennsylvania, where they once suggested he would compete aggressively but has not.

The bickering between campaigns was supposed to take a break Thursday night as both candidates address the Alfred E. Smith Memorial Foundation Dinner, a white-tie gala at New York City's Waldorf Astoria Hotel that has been a required stop for politicians since the end of World War II.

The evening's political dinner is named for the four-term Democratic governor of New York who lost the 1928 presidential race to Republican Herbert Hoover. Smith was the first Catholic to run for president and the dinner named for him is organized by the Catholic Archdiocese of New York for the benefit of needy children.

In keeping with tradition, both candidates prepared lighthearted remarks for the event. That was also the case four years ago when Obama and GOP nominee John McCain poked fun at themselves and each other just a day after an intense presidential debate at Hofstra University on Long Island.

As in 2008, this year's dinner follows a confrontational debate, also at Hofstra, lending an air of drama to the pivot from acrimony to humor.

Democrats are pushing the accusation that Romney is being dishonest, taking up Obama's refrain since Tuesday's debate that the GOP nominee is offering "a sketchy deal."

"I don't think they were just sketchy," Biden said at a rally in Las Vegas. "I think they were Etch-a-Sketchy."

Obama and Biden are to campaign together next Tuesday in Ohio after Monday night's final debate.

On Libya, Obama has faced scrutiny for shifting explanations of what happened. He pushed back on Thursday.

"We weren't confused about the fact that four Americans had been killed," Obama said.

"I wasn't confused about the fact that we needed to ramp up diplomatic security. ... I wasn't confused about the fact that we had to investigate exactly happened so it gets fixed. And I wasn't confused about the fact that we're going to hunt down whoever did it and bring them to justice," the president said.

On another national security issue, Obama said he still wants to close the prison for terrorism suspects at Guantanamo Bay, Cuba, a big unmet promise of his 2008 campaign. The effort was blocked by Congress, which passed a law prohibiting the government from moving prisoners to the U.S. for detention or trial.

Earlier, in Nevada, Biden accused GOP vice presidential nominee Ryan of sharing a cynical vision of Americans with Romney.

"Ryan has written a book called the 'Young Guns' with two other members of the House," Biden said. "Unfortunately, the bullets are aimed at you."

Romney campaign spokesman Brendan Buck responded that Biden's "over-the-top rhetoric" was disappointing but not surprising.

"In the absence of a vision or plan to move the country forward, the vice president is left only with ugly political attacks beneath the dignity of the office he occupies," Buck said in a statement emailed to reporters.

The finger-pointing comes after the heated debate this week between Obama and Romney. The GOP nominee's oldest son, Tagg, was asked by a North Carolina radio host Wednesday how it feels to hear the president "call your dad a liar" - a word Obama never used although he repeatedly said Romney's statements weren't true.

Tagg Romney laughed at the question. "You want to rush down the debate stage and take a swing at him. But you know you can't do that because, well first cause there is a lot of Secret Service between you and him, but also because it's the nature of the process," he said.

Another Romney son, Josh, said on ABC's "The View" on Thursday that his brother didn't mean it but was responding to the emotions that arise in the heat of the campaign.

"That brother has slugged me a couple times. I assure you President Obama has nothing to worry about," Josh Romney quipped. "You really don't like to see your dad get beat up by the media or President Obama or whatever it is, so you take it pretty personally. But I think that was just something he was saying off the cuff and I assure you he didn't mean it."

Their mother, Ann Romney, also appearing on "The View," said the negativity of the campaign is very difficult for their family and she initially didn't want to go through another campaign after losing the 2008 Republican primary. She said she agreed to a second run because she feels her husband is uniquely qualified to bring economic hope and prosperity to America

But she didn't hesitate when co-host Barbara Walters asked whether her husband's political career will end if he doesn't win on Nov. 6.

"Absolutely," Mrs. Romney said. "He will not run again, nor will I."

The president campaigned earlier Thursday in tightly contested New Hampshire and asked the state's voters to give him more time in office to get the economy back on track. "I need your help to finish what we started in 2008."

On the celebrity front, Obama picked up the endorsement of rock star Bruce Springsteen, who also backed the Democrat in 2008 and Thursday campaigned for him in Ohio with former President Bill Clinton.

"For 30 years I've been writing about the distance between the American dream and American reality," Springsteen said, reading from a statement on his music stand. "Our vote is the one principal way we get to determine that distance."

Associated Press writers Nedra Pickler and Ken Thomas in Washington, Thomas Beaumont in Norfolk, Va., and Tamara Lush in Ocala, Fla., contributed to this report.