Obama's lead slips to 3 points . . .

By Andrew Quinn

WASHINGTON (Reuters) - Democrat Barack Obama's lead over Republican John McCain in the presidential race has dropped to 3 points, according to a Reuters/C-SPAN/Zogby poll released on Sunday.

Obama leads McCain by 48 to 45 percent among likely U.S. voters, down 1 percentage point from Saturday. The four-day tracking poll, which has a margin of error of 2.9 points.

Pollster John Zogby said the numbers were good news for McCain, and probably reflected a bump following his appearance in the third and final presidential debate on Wednesday.

"For the first time in the polling McCain is up above 45 percent. There is no question something has happened," Zogby said.

He said the Arizona senator appeared to have solidified his support with the Republican base -- where 9 out of 10 voters now back him -- and was also gaining ground among the independents who may play a decisive role in the November 4 election.

Obama's lead among independent voters dropped to 8 points on Sunday from 16 points a day earlier.

'RED FLAGS'

"If that trend continues, it is something that has got to raise red flags for Obama," Zogby said. "It suggests to me that his outward look of confidence may be as much strategy as it is real."

Other national polls have given Obama a double-digit overall lead, fueled by perceptions he would do a better job managing the faltering economy and unhappiness with McCain's attacks on him over the past week.

But he has cautioned his supporters against overconfidence and most polls now put his lead in single digits.

Obama, 47, who would be the first black president, enjoys strong support among black, Hispanic, Catholic and Jewish voters while the 72-year-old McCain holds a narrower lead among male and white voters.

Women, who are expected to be an important factor in the election, still favor Obama by a 6-point margin, although this has been declining in recent days.

Independent Ralph Nader drew 2 percent support in the poll, conducted Saturday through Tuesday, while Libertarian Bob Barr registered 1 percent, both little changed.

The rolling tracking poll surveyed 1,210 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.

The U.S. president is determined not by the most votes nationally but by a majority of the Electoral College, which has 538 members allotted to all 50 states and the District of Columbia in proportion to their representation in Congress.