That is a significant swing from the most recent ABC/Washington Post poll earlier this month that gave McCain a slight 49-47 point edge.
"It is all about the economy," ABC's chief Washington correspondent George Stephanopoulos told "Good Morning America" today. "People are angry and shocked and worried about the economy and that is all helping Barack Obama right now."
The latest poll finding marks the first time that the Illinois senator has surpassed 50 percent support among likely voters in the presidential campaign -- a key coup for the Democratic candidate.
"You have to go back to 1948 for the last time when a candidate having this kind of a lead in late September lost," Stephanopoulos said.
Neither of the last two Democratic nominees, former Vice President Al Gore in 2000 or Sen. John Kerry in 2004, broke the 50 percent mark in pre-election ABC News/Washington Post polls.
Obama More Trusted to Handle Economy
Obama has squashed McCain's convention gains by convincing voters that he can better address the nation's economic crisis and is more in tune with the economic troubles voters now face.
An earlier ABC News/Washington Post poll on Sept. 7 found that on trust to handle the nation's economy, Obama led McCain by about five percentage points.
"Now it's up to a 14-point lead for Obama on trust to handle the economy," Stephanopoulos said.
On the question of which candidate voters feel understands the Americans economic problems better, Obama now has a 24 percentage point lead over the Arizona senator.
"Barack Obama is blowing away John McCain on that point," Stephanopoulos added. "They say he gets it."
Obama Erased McCain Edge Among White Women Voters
Two weeks ago, McCain came out of the Republican Party convention with his new running mate, Sarah Palin, at his side along with a substantial advantage among white voters and newfound strength among white women voters.
However the latest ABC/Post poll finds Obama has narrowed the gap to within five percentage points among white voters overall, and the two candidates now run about even among white women.
"He's only getting 77 percent of Hillary Clinton voters, but he's doing far better with Democrats overall getting 88 percent of Democrats," Stephanopoulos said.
The poll also found the governor of Alaska has some of her luster among voters.
"There was a big Sarah Palin effect coming out of the Republican convention," Stephanopoulos said. "She had high favorable ratings. She's coming back down to earth a little bit. Her favorable rating has gone from 58 [percent] on Sept. 7 down to 52 percent now, so a little bit of a deflation there."
The ages of the presidential candidates have also become an issue for voters, according to the ABC/Post poll. McCain is 72 while Obama is 47. "More and more people are worried about age," Stephanopoulos said. "Forty-eight percent of voters say they see that age is an issue. And if you think age is an issue, those 48 percent of voters, they break heavily for Barack Obama by 30 points."
McCain Holds Key to Bailout on Capitol Hill
Obama and McCain face a key test this week on how they handle the administration's proposed $700 billion bailout plan for Wall Street.
Both presidential candidates agree that the administration's plan should include caps on executive compensation, or golden parachutes. But it is McCain who may ultimately hold the fate of the massive bailout plan in his hands.
"The big factor may be John McCain. I was talking to top Republicans and Democrats yesterday, they both say that if John McCain doesn't vote for this package, it is going to go down," Stephanopoulos said. "So he is facing a huge choice, a huge gamble also for McCain," he added.
"McCain aides say he hasn't made up his mind yet. He's laid out his own conditions as well but they want him to be seen and he wants to be seen as a champion of the little guy," Stephanopoulos said.
"The Democrats say they're not going to give John McCain a free chance to break away from President Bush," Stephanopoulos said. "The Republican members of Congress say that if he votes 'no' that they're not going to be at odds with him."
Stephanopoulos said the Bush administration's massive $700 billion Wall Street bailout package isn't a done deal on Capitol Hill. Administration officials are pressing to get the bill passed by this weekend.
"Top officials tell me in Congress that 'It's not soup yet.' There is no deal yet. They're pushing to improve, they say, improve the bailout plan saying it has to do something to constrain executive compensation. Something to give taxpayers equity in this deal. Something to help homeowners facing foreclosure," he said.
"It's tough to see right now. There is still a lot of negotiating going on right now," Stephanopoulos said.