Bolstered by the fiscal crisis and deep concerns about the direction of the country, Mr. Obama has seemed to solidify the support he has gained in recent months. When likely voters were asked whom they would vote for in an expanded field that included several third-party candidates, Mr. Obama got the support of 52 percent of them, Mr. McCain 39 percent, Bob Barr 1 percent, and Ralph Nader 2 percent.

The nationwide telephone poll was conducted Saturday through Wednesday with 1,439 adults nationwide, including 1,308 registered voters. The margin of sampling error is plus or minus three percentage points.

The poll was conducted as a wide range of state polls have shown Mr. Obama, of Illinois, ahead or tied in several crucial contested states, including some traditionally Republican states that Mr. McCain, of Arizona, must carry to win the election.

The survey suggested that Mr. Obama’s candidacy  if elected, he would be the first black president  has changed some perceptions of race in America. Nearly two-thirds of those polled said whites and blacks have an equal chance of getting ahead in today’s society, up from the half who said they thought so in July. And while 14 percent still said most people they knew would not vote for a black presidential candidate, the number has dropped considerably since the campaign began.

Mr. McCain’s heavy focus on taxes in the final weeks of the campaign seems to be having some effect, the poll found. Forty-seven percent of voters said Mr. McCain would not raise taxes on people like them, up from just 38 percent who said so two weeks ago. (And 50 percent said they thought Mr. Obama would raise taxes on people like them, while 44 percent said he would not; both numbers are similar to two weeks ago.)

With just days until Americans choose a new president, the survey found them deeply uneasy about the state of their country. Eight-five percent of respondents said the country was pretty seriously off on the wrong track, near the record high recorded earlier this month. A majority said the United States should have stayed out of Iraq. And President Bush’s approval rating remains at 22 percent, tied for the lowest presidential approval rating on record (which was President Harry S. Truman’s rating, recorded by the Gallup Poll in 1952).

Mr. McCain’s renewed efforts to cast himself as the candidate of change have apparently faltered. Sixty-four percent of voters polled said Mr. Obama would bring about real change if elected, while only 39 percent said Mr. McCain would. And despite Mr. McCain’s increased efforts to distance himself from President Bush, a majority still said he would generally continue Mr. Bush’s policies.