PRINCETON, NJ -- Barack Obama has returned to a slight three percentage point lead over John McCain in Gallup Poll Daily tracking for Aug. 15-17, with Obama at 46% and McCain at 43% among registered voters.

The current position of the race is representative of the overall average positioning of the two candidates so far this summer. Although McCain moved closer to Obama in the last three reports of Gallup's tracking, he was not able to sustain this tied position, and the bottom line is that the race appears to have once again returned to just about where it has been on average over the summer. (To view the complete trend since March 7, 2008, click here.)

Campaign activity from this point forward will begin to intensify, with the pending announcement of Obama's vice-presidential choice, the Democratic convention, McCain's own announcement of his vice president, and the Republican convention. The degree to which all of these events will affect voter preferences in the presidential race could go a long way towards determining the eventual winner of the election in November. -- Frank Newport

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 Aug. 15-17, 2008. For results based on this sample of 2,660 registered voters, 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.

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