Democratic presidential candidate, Senator Barack Obama, and his wife, Michelle, embrace during a rally last Tuesday at Bicentennial Park in Miami.

WASHINGTON (AP):

The presidential race tightened after the final debate with John McCain gaining among whites and people earning less than $50,000, according to an Associated Press-GfK poll that shows McCain and Barack Obama essentially running even among likely voters in the election homestretch.

The poll, which found Obama at 44 per cent and McCain at 43 per cent, supports what some Republicans and Democrats privately have said in recent days - that the race narrowed after the third debate as Republican-leaning voters drifted home to their party.

Three weeks ago, an AP-GfK survey found that Obama had surged to a seven-point lead over McCain, lifted by voters who thought the Democrat was better suited to lead the United States through its sudden economic crisis.

The contest is still volatile, and the split among voters is apparent less than two weeks before the November 4 election.

The new AP-GfK head-to-head result is a departure from some, but not all, recent national polls.

Obama and McCain were essentially tied among likely voters in the latest George Washington University Battleground Poll, conducted by Republican strategist Ed Goeas and Democratic pollster Celinda Lake. In other surveys, focusing on likely voters, a Washington Post-ABC News poll showed Obama up by nine percentage points, while a poll by the non-partisan Pew Research Centre had Obama leading by 14.

Obama ahead

A Wall Street Journal/NBC News poll, among the broader category of people registered to vote, found Obama ahead by 10 points.

Polls are snapshots of highly fluid campaigns. In this case, there is a margin of error of plus or minus 3.5 percentage points. That means Obama could be ahead by as many as eight points or down by as many as six. There are many reasons why polls differ, including methods of estimating likely voters and the wording of questions.