In a set of dueling interviews aired Sunday night, President Obama conceded his "biggest disappointment" is that he hasn't significantly changed the tone in Washington since taking office -- and acknowledged sometimes his campaign ads go "overboard" and contain "mistakes."
Mitt Romney, meanwhile, touted his campaign's competitiveness as he emerged from a rocky week. "We've got a campaign which is tied with an incumbent president to the United States," Romney told CBS' "60 Minutes."
The Republican presidential nominee said his campaign, despite heat from the media and grumbling from some conservatives, "doesn't need a turnaround." Romney expressed confidence he's "going to win this thing."
The interviews aired as both candidates were launching a new wave of campaigning. Romney arrived in Colorado Sunday for the start of a weeklong tour through battleground states. Obama's campaign on Monday launched a new offensive with a TV ad blasting Romney for criticizing Americans who don't pay income taxes without having "come clean" about his own.
At the same time, Obama told CBS that his ads are not always 100 percent accurate.
"Do we see sometimes us going overboard in our campaign, are there mistakes that are made, areas where there is no doubt that somebody could dispute how we are presenting things? You know, that happens in politics," Obama said, arguing that the "vigorous debate" helps better define each candidate's vision. The exchange was not aired on television but was posted online.
Amid the sustained toughness of the campaign trail tone, Obama conceded to "60 Minutes" that the tone in Washington remains more caustic than he'd like.
"Change has happened and positive change for the American people," Obama said, adding: "I'm the first one to confess that the spirit that I brought to Washington, that I wanted to see instituted, where we weren't constantly in a political slugfest but were focused more on problem solving that, you know, I haven't fully accomplished that."
Obama said he hasn't "even come close in some cases."
"And, you know, if you ask me what's my biggest disappointment, is that we haven't changed the tone in Washington as much as I would have liked," the president said, adding that "as president I bear responsibility for everything, to some degree."
Obama also defended his foreign policy record amid anti-American rage in the Muslim world, firing back at suggestions from Romney that the president has been weak with allies and enemies alike.
In the interview Sunday night the president said, "If Gov. Romney is suggesting that we should start another war, he should say so."
In the companion interview to Obama's appearance on CBS' "60 Minutes," Romney broadened his reproach to include Israel, criticizing Obama's failure to meet with the U.S. ally's head of state, Benjamin Netanyahu, during the annual U.N. gathering. Romney called it a mistake that "sends a message throughout the Middle East that somehow we distance ourselves from our friends."
The White House has said scheduling precluded a meeting between the two leaders, who won't be in New York at the same time. With the final six weeks of a hard-fought election hanging over the U.N. summit, Obama has opted out of face-to-face meetings with any of his counterparts -- not just Netanyahu -- during his compressed U.N. visit.
But Obama pushed back on the notion that he feels pressure from Netanyahu, dismissing as noise the Israeli leader's calls for the U.S. to lay out a "red line" that Iran's nuclear program must not cross to avoid American military intervention.
"When it comes to our national security decisions, any pressure that I feel is simply to do what's right for the American people," Obama said. "And I am going to block out any noise that's out there."
In a wide-ranging interview conducted the day after U.S. Ambassador to Libya Chris Stevens was killed in an attack on Benghazi, Obama defended his foreign policy successes, noting he'd followed through on a commitment to end the war in Iraq and had nabbed Al Qaeda leader Usama bin Laden.
He also waxed optimistic that winning a second term would give him a mandate to overcome obstructionism from congressional Republicans whose No. 1 goal, he said, has been to prevent his re-election.
"My expectation is, my hope is that that's no longer their No. 1 priority," Obama said. "I'm hoping that after the smoke clears and the election season's over that that spirit of cooperation comes more to the fore."
Romney, in an interview conducted last week, sought to deflect attention from his running mate, Wisconsin Rep. Paul Ryan, over their differences in Medicare policy: "I'm the guy running for president, not him."
While reaffirming his commitment to lowering all income tax rates by 20 percent, Romney expressed no unease about his refusal to offer specifics, such as which loopholes and deductions he'd eliminate to pay for the cuts.
"The devil's in the details. The angel is in the policy, which is creating more jobs," Romney said, adding that he doesn't want to see overall government revenue reduced.
Romney, after releasing tax returns showing he paid an effective rate of 14.1 percent last year, also defended the rate -- saying the tax on investments is relatively low "to encourage economic growth."
Interviewer Scott Pelley had asked Romney if the rate was "fair" to someone making $50,000 and paying a higher rate. However, Romney's rate is not that out of sync with that of other Americans. A Tax Foundation report found at least 90 percent of Americans recently had a lower effective rate than the 13.9 percent rate Romney had in his earlier 2010 filing.
The "60 Minutes" interviews came as Romney's campaign strives to turn the page after a secretly recorded video showed Romney writing off his prospects for winning over the almost half of Americans who he said pay no taxes, are dependent upon government and see themselves as victims. Ahead of an evening campaign stop at a Denver-area high school Sunday, Romney huddled with senior advisers in Los Angeles to rehearse for the three upcoming presidential debates, which his aides see as the best opportunity to get his campaign and its message back on track.
Amid mounting pressure to spend less time raising money and more time explaining his plans to voters, Romney was refocusing his schedule on the most competitive states. After Colorado, Romney was to begin a three-day bus tour in Ohio on Monday followed by a stop in Virginia -- states that Obama won in 2008 but that Republicans claimed four years earlier.
While national polls remain tight, polls in several of the most closely watched states, including Colorado, suggest Obama has opened narrow leads. Obama won Colorado by 9 points four years ago, but the state went to a Republican in the previous three presidential elections.
The Associated Press contributed to this report.