They also clashed on health care, and few issues divide the candidates and their parties more than that issue. The 2010 federal health care law championed by Obama would require nearly everyone to get coverage by 2014. Romney sees the plan as a dangerous government takeover.

They also differ on how seniors should obtain care. Obama wants to retain traditional Medicare, which faces a severe financial crisis. He would save $716 billion from anticipated spending in the future, and save part of that money by having an independent commission recommend ways to cut costs.

Romney fired away at that notion and insisted his plan, which would provide federal help for seniors so they could choose Medicare or a private plan, was far more efficient.

“I know my own view is I’d rather have a private plan. I’d just as soon not have the government telling me what kind of health care I get. I’d rather be able to have an insurance company. If I don’t like them, I can get rid of them and find a different insurance company. But people make their own choice,” he said.

No, Obama countered. Private plans will insure the healthiest seniors, leaving Medicare to take the most ailing. “And when you move to a voucher system, you are putting seniors at the mercy of those insurance companies. And over time, if traditional Medicare has decayed or fallen apart, then they’re stuck,” the president said.

Obama recalled how Romney signed into law the Massachusetts health care plan widely seen as a model for the federal program.

“There’s a reason why Gov. Romney set up the plan that he did in Massachusetts. It wasn’t a government takeover of health care. It was the largest expansion of private insurance,” Obama said.

Romney defended his plan, noting that it raised no taxes. But, he added, “The federal government taking over health care for the entire nation and whisking aside the 10th Amendment, which gives states the rights for these kinds of things, is not the course for America to have a stronger, more vibrant economy But what it does say is that insurers, you’ve got to take everybody."

The candidates will debate again Oct. 16 in Hempstead, N.Y., and on Oct. 22 in Boca Raton, Fla. Vice President Joe Biden will debate Republican nominee Rep. Paul Ryan of Wisconsin on Oct. 11 in Danville, Ky.

Obama has an edge over Romney in most national and swing state polls. But Romney holds the edge on the economy. A Gallup poll released Wednesday found that voters think Romney would better handle the economy by 49 percent to 45 percent. The survey also showed slightly more voters think the economy will be better if Romney wins.

Part of the voters’ judgment is likely to involve their perceptions of how things are going, and economic indicators are mixed. Unemployment has topped 8 percent since February 2009, the month after Obama took office, an unusually long stretch for such a high rate. But the president can argue that unemployment has slowly dropped since its 10 percent peak two years ago.

The economy grew at a sluggish 1.3 percent annual rate in the second quarter of this year, hardly considered a healthy pace. But it did grow, and it has been expanding since the Great Recession of 2007-09 ended more than three years ago.

Consumer confidence, a key barometer of public mood, jumped last month, but even that spike only brought it back to its February level, according to data compiled by the Conference Board, a New York-based research group.

And household income continues to lag. A study by Sentier Research found that in the three years ending in June, inflation-adjusted median household income tumbled 4.8 percent, even worse than the 2.7 percent drop during the recession itself.