PRINCETON, NJ -- Barack Obama's advantage over John McCain in the presidential race has again widened to 10 percentage points among registered voters, 52% to 42%, in Gallup Poll Daily tracking from Oct. 16-18.

This is the first Gallup Poll Daily tracking report based on data collected entirely after Wednesday night's third and final presidential debate. McCain's current 42% support level is at the midpoint of the 41% to 43% range he has received over the past 18 days. Obama's 52% is at the upper end of the 48% to 52% range of support he has received over the same time period. (To view the complete trend since March 7, 2008, click here.)

With 1% of registered voters saying they will vote for another specific candidate, only 6% remain undecided, one of the smallest levels to date.

A Tighter Race Among Likely Voters

Gallup is also looking at the race according to two likely voter scenarios. One, the traditional Gallup approach, takes into account voters' intention to participate in the current election as well as their voting history in previous presidential elections. Among this group, Obama leads McCain by three points, 49% to 46%. This is similar to Obama's standing among traditional likely voters over the past five days.

An alternate approach to defining likely voters uses only voters' self-professed likelihood to vote in 2008, and does not factor in whether they voted in past elections. This model assumes that new registrants and infrequent voters will be more heavily represented in the pool of voters who turn out on Election Day than has been the case historically. Among this more broadly defined likely voter group, Obama leads by seven points, 51% to 44%. -- Lydia Saad

(Click here to see how the race currently breaks down by demographic subgroup.)

Survey Methods

For the Gallup Poll Daily tracking survey, Gallup is interviewing no fewer than 1,000 U.S. adults nationwide each day during 2008.

The general-election results are based on combined data from Oct. 16-18, 2008. For results based on this sample of 2,798 registered voters, the maximum margin of sampling error is ±2 percentage points.

For results based on the sample of 2,590 "traditional" likely voters (based on the model taking into account current voting intention and past voting behavior), the maximum margin of sampling error is ±2 percentage points.

For results based on the sample of 2,277 more broadly defined likely voters (based on the model taking into account current voting intention only), the maximum margin of sampling error is ±2 percentage points.

Interviews are conducted with respondents on land-line telephones (for respondents with a land-line telephone) and cellular phones (for respondents who are cell-phone only).

In addition to sampling error, question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of public opinion polls.