Obama's edge among women, an important swing voting bloc in the November 4 election, grew from 9 to 12 points. Obama also gained among Hispanics and young voters and leads by 10 points among independents.

Obama's edge has expanded amid intensifying economic fears as financial markets have tumbled this week. Half of the polling, conducted Monday through Thursday, was done after Tuesday's second presidential debate.

"Obama is benefiting from the terrible economic news and what was seen to be a relatively poor debate performance by McCain," pollster John Zogby said.

McCain, 72, a former Navy fighter pilot and Vietnam prisoner of war, fell behind Obama among voters with a member of the military in their family. The Arizona senator runs even with Obama among voters older than 65.

"McCain is not doing well with the groups he needs to succeed," Zogby said. "We're not ready to call it a tailspin, but he is slipping."

Obama, an Illinois senator, has solidified his lead in most national polls in recent weeks as the Wall Street crisis focused attention on the economy, where polls show voters have more faith in Obama's leadership.

Independent Ralph Nader had the support of 2 percent of poll respondents and Libertarian Bob Barr registered 1 percent. Four percent of voters said they were still undecided.

The rolling tracking poll surveyed 1,203 likely voters in the presidential election. In a tracking poll, the most recent day's results are added while the oldest day's results are dropped in an effort to track changing momentum.