By John Whitesides
WASHINGTON (Reuters) - Democratic challenger John Kerry expanded his slight lead over President Bush to three points in a tight race for the White House, according to a Reuters/Zogby poll released on Monday.
The Massachusetts senator held a 47-44 percent lead over Bush in the latest three-day tracking poll, up two points from Sunday. Bush's support dropped one point and Kerry's support rose one point in the new poll.
The close race turns up the pressure for Wednesday's final debate in Tempe, Arizona, when the White House rivals will have another chance to make their case to voters on domestic issues.
The poll found six percent of likely voters are still undecided about the race with barely more than three weeks to go until the Nov. 2 election, and 16 percent of the voters who identify themselves as independents are undecided.
Bush made small gains among young voters and Kerry picked up strength among women voters ahead of the debate -- the final chance for both candidates to speak directly to an audience of millions of voters.
"Wednesday's debate is vital because many sub-groups remain close and because so many independents have yet to make up their minds," pollster John Zogby said.
The poll of 1,214 likely voters was taken Friday through Sunday and has a margin of error of plus or minus 2.9 percentage points. The rolling poll will continue through Nov. 1 -- the day before the election.
The last two days of polling came after Bush and Kerry battered each other over Iraq, jobs and taxes during a debate on Friday. The economy and Iraq are consistently listed as the top issues in the race.
A tracking poll combines the results of three consecutive nights of polling, then drops the first night's results each time a new night is added. It allows pollsters to record shifts in voter sentiment as they happen.
The poll found 48 percent of voters thought the United States was headed in the wrong direction and 45 percent thought it was headed in the right direction.
It also showed independent candidate Ralph Nader, blamed by some Democrats for drawing enough votes from Al Gore to cost him the election in 2000, earning the support of 1.7 percent of likely voters.