Obama has slim 2-point lead on McCain

NASHVILLE, Tennessee (Reuters) - Democratic presidential candidate Barack Obama has a slim 2-point lead on Republican rival John McCain in a tight White House race, according to a Reuters/C-SPAN/Zogby poll released on Wednesday.

Obama led McCain by 47 percent to 45 percent in the national poll, within the margin of error of 2.8 percentage points. Obama led by 3 points in Tuesday's poll.

Four percent of voters said they were still undecided.

The daily tracking poll, which will sample public opinion until the November 4 election, showed Obama leading among two crucial swing voting blocs. He has a 9-point advantage among independents and a 7-point edge among women.

"This race is at equilibrium," pollster John Zogby said, adding neither candidate has been able to take full advantage of voter unhappiness with the country's direction.

"We are seeing an electorate that is frustrated with Washington," he said.

Obama has solidified his lead in most national polls in recent weeks as the Wall Street crisis focused attention on the economy, an area of strength for the Illinois senator.

Zogby's poll was taken Sunday through Tuesday, with the calls concluding before McCain and Obama tangled over taxes and the economic crisis during the second of their three scheduled debates on Tuesday in Nashville, Tennessee.

Independent Ralph Nader and Libertarian Bob Barr each registered support from 1 percent of respondents in the poll.

The rolling tracking poll surveyed 1,220 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.

(Editing by Bill Trott)