WASHINGTON (Reuters) - Democrat Barack Obama has a 2-point lead in the U.S. presidential race on Republican John McCain, whose choice of Sarah Palin as his running mate helped shore up support for both candidates, according to a Reuters/Zogby poll released on Wednesday.

Obama leads McCain among likely voters by 47 percent to 45 percent, within the poll’s 3.1 percent margin of error. He gained ground in the last month among independent and women voters and on the question of who could best manage the faltering U.S. economy.

Obama wiped out McCain’s 5-point edge in a Reuters/Zogby poll taken in August before the nominating conventions, a sign the Arizona senator could be drifting back to earth from what other opinion polls showed was a post-convention surge.

“We’re back to where we always thought we would be -- in a very competitive race,” pollster John Zogby said.

The poll, taken Thursday through Saturday, follows a hectic month in the race to the November 4 election as both parties held their nominating conventions and both candidates selected their vice presidential running mates.

McCain’s choice of Sarah Palin, an anti-abortion and pro-gun first-term governor from Alaska, as his No. 2 set off a political firestorm that helped stoke conservative enthusiasm for the Republican ticket.

But Zogby said Palin also helped solidify Democratic support for Obama. “For the last few weeks it’s been all about Palin and she has been a divisive force,” he said. “She has shored up the base for both candidates.”

Obama, who struggled to solidify Democrats in August when just 74 percent backed him, now has the support of 89 percent of Democrats. McCain’s support among Republicans grew from 81 percent last month to 89 percent.

Nearly one-third of likely voters said the choice of Palin made them more likely to support McCain and nearly one-quarter said it made them less likely. About 43 percent said it would have no effect.

Obama’s selection of Delaware Sen. Joe Biden, chairman of the Senate Foreign Relations Committee, as his No. 2 had less impact. About 23 percent said they were more likely to vote for Obama with Biden on the ticket and 16 percent said they were less likely.

MCCAIN STILL LEADS ON ECONOMY

Half of all voters said the economy was the top issue, and the poll showed McCain narrowly led Obama on the question of which candidate could best manage the economy by 47 percent to 45 percent.

But that was a significant gain for Obama from McCain’s 9-point advantage last month. The poll was taken before Sunday’s upheaval on Wall Street with the fall of Lehman Brothers Holding and the sale of Merrill Lynch.

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Obama has tried to refocus the campaign on his proposals for the economy after a Republican convention where he was heavily criticized as a liberal elitist unfamiliar with the struggles of working families.

The Illinois senator wiped out McCain’s 5-point August lead among independents and expanded his edge over McCain among women, two crucial swing voting blocs in November.

Obama now has a statistically insignificant 1-point edge over McCain among independents and has a 7-point lead among women, up from a 2-point advantage last month.

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He also gained ground among Catholics and older voters, but lost support to McCain among suburban voters and small-town residents. Palin has made her background as the mayor of Wasilla, a town of about 9,000 residents, a key component of her political biography.

The poll found McCain and Obama were in an absolute dead heat at 45 percent when independent candidate Ralph Nader and Libertarian Party candidate Bob Barr were added to the mix. Nader earned 2 percent and Barr 1 percent of the vote.

The telephone poll of 1,008 likely voters had a margin of error of 3.1 percentage points.

The poll was taken as McCain and Obama head into three potentially crucial debates beginning on September 26 in Oxford, Mississippi. Palin and Biden will hold one debate on October 2 in St. Louis.