WASHINGTON -- A new Associated Press-GfK poll shows President Barack Obama and Republican challenger Mitt Romney still in a virtual tie with the Nov. 6 election just weeks away, but voters expressed more optimism about the struggling economy.

The poll was taken before the furor over remarks Romney made in a secretly taped video nearly four months ago, in which he told a group of wealthy donors that nearly half of Americans believe they are victims and entitled to government support. "I'll never convince them they should take personal responsibility and care for their lives," Romney said in the video, posted online Monday by the left-leaning Mother Jones magazine.

The new poll, released Wednesday, showed 47 per cent of likely voters backed Obama, while 46 per cent sided with Romney. Among all adults, Obama is favoured by 52 per cent of Americans, with 37 per cent for Romney.

"This has not been the best three weeks in the history of American politics for the Romney campaign," Republican consultant Rich Galen said. But he said the economy remains "a great weight around the ankles of Obama."

In an interview Tuesday on the conservative-leaning Fox News, Romney said he didn't intend to write off any part of a deeply divided electorate, including seniors or members of the military, who along with the poor often pay no taxes. But he said "I'm not going to get" votes from people who believe the government's job is to redistribute wealth.

Romney has neither disavowed nor apologized for his remarks in the video. Instead, he has cast his comments as evidence of a fundamental difference with Obama over the economy, adding the U.S. government should not "take from some to give to the others."

The U.S. income tax is designed to be progressive, so those who earn the most theoretically pay the most. Through programs as diverse as health care and food stamps, the government collects tax revenue and pays it out in the form of benefits for those who qualify.

"My course for the American economy will encourage private investment and personal freedom," Romney wrote in an op-ed essay in Wednesday's USA Today.

Obama addressed the Romney claims in an appearance on the David Letterman talk show that aired late Tuesday.

"One thing I've learned as president is that you represent the entire country," Obama said

Meanwhile, an independent group supporting Obama ran the first television advertisement using the leaked video. The Priorities USA Action ad shows clips of Romney saying 47 per cent of Americans "believe that they are victims" and ends with a narrator saying Romney will never convince middle-class voters he's on their side.

With early voting scheduled to be under way in two dozen states by week's end, just 17 per cent of likely voters remain undecided or say they might change their minds. Both campaigns hope to lock in votes long before Election Day. The first of three presidential debates is scheduled for Oct. 3.

Obama planned a rare full day at the White House Wednesday, including a private meeting with Myanmar democracy leader Aung San Suu Kyi. Romney scheduled a fundraiser in Atlanta and two appearances in Miami, including a candidate forum with the Spanish-language TV network Univision.

The new Associated Press-GfK Poll was conducted Sept. 13-17. While Obama has seen a general upswing in voter opinion, the poll shows 61 per cent of likely voters describe the economy as poor. Just over half think the economic outlook has gotten worse over the last four years. And 57 per cent think unemployment will get worse or stay the same over the next four years.

But a growing number of voters thinks circumstances will get better in the coming year -- 48 per cent, up from 41 per cent before the Democratic and Republican national conventions a few weeks ago.

The sluggish economy and lingering high unemployment are by far the overriding issues of the election, and Romney's case for the presidency is based on his claim that his success as a businessman proves he will succeed in creating jobs in a nation where unemployment is 8.1 per cent.

Obama and the Democrats have tried to counter by depicting Romney as a multimillionaire who has some of his wealth invested in the Cayman Islands and elsewhere overseas and is out of touch with the needs of middle class Americans.