PRINCETON, NJ -- The latest Gallup Poll Daily tracking update finds a precise tie between John McCain and Barack Obama, with 45% of nationwide registered voters currently supporting each candidate for president.

The two have been closely matched in Gallup Poll Daily tracking for the last 11 days, with neither candidate enjoying a statistically significant lead (though Obama has typically held a slim advantage). Thus, the candidates enter this intense, back-to-back convention period even, after Obama enjoyed a slight advantage throughout the summer. The National Democratic Convention begins Monday in Denver with the Republicans' convention begins Sept. 1 in Minneapolis. (To view the complete trend since March 7, 2008, click here.)

On Saturday, after much speculation, Obama finally named his vice presidential running mate, Delaware Sen. Joe Biden. Initial public reaction to Biden's selection appears rather unenthusiastic, according to a special Biden reaction poll conducted by USA Today and Gallup on Saturday.

Typically, presidential candidates have gotten a bump in the polls after naming their vice presidential running mate. Obama apparently received no immediate benefit in the polls from naming Biden as Gallup Poll Daily tracking interviews conducted during the day on Saturday still showed Obama and McCain closely matched in voter preferences for president.

The first Gallup three-day rolling average in which all interviews will have been conducted entirely after the announcement of Obama's vice presidential selection will be reported by Gallup on Tuesday, and will give a clearer assessment of its impact on voter preferences in the presidential race. -- Jeff Jones

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. 21-23, 2008. For results based on this sample of 2,625 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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