Polls in several of the most contested states also show the president with a slight edge.
Democrats say Obama has gained an advantage on the economy in part because Romney hasn't laid out specific plans for what he would do differently. And they see signs that voters, even those who say their economic situation isn't better today, believe it will be in a year or two, making it more likely they'll want to stick with Obama.
Romney's campaign advisers say Obama hasn't done anything to change the dynamic on the economy and claim any Obama gains are in states that would back the president in the fall anyway.
Republican outside groups acknowledge Obama has gotten a burst of support across the board, including on the economy, since his convention wrapped up just over a week ago. But they insist the race is still within reach or statistically tied in key states and nationally.
The economy remains weak, and there's no telling who voters will trust more to handle it come November.
Unemployment dropped to 8.1 percent last month, but only because more people stopped looking for work. Acknowledging the tenuous situation, the Federal Reserve announced this week that it would spend $40 billion a month to buy mortgage bonds for as long as it deems necessary to make home buying more affordable. It also plans to keep short-term interest rates at record lows through mid-2015 in an effort to jump-start the listless American economy.
On Saturday, Romney's running mate, Wisconsin Rep. Paul Ryan, called the Fed's action "sugar high economics" that would help banks and Wall Street, but not average Americans.
"We don't need synthetic money creation," Ryan said during a campaign stop in Oldsmar, Fla. "We need economic growth."
Noticeably absent from that list of states where Obama's new 60-second ad was running: North Carolina. Obama narrowly won the state in 2008, moving it into the Democratic column for the first time in nearly 40 years. But Democrats say he faces an uphill battle there in November given the state's dour economy and its shift back to the right in statewide elections.
Obama's campaign said cutting North Carolina out of its latest ad buy was not an indication that it was giving up on the state. The campaign is expected to spend just under $1 million in new ads in North Carolina next week.
Associated Press writers Kasie Hunt in Washington, Steve Peoples in Boston and Ken Thomas in Belmont, Mass., contributed to this report.
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