Any bump Democratic presidential candidate Sen. Barack Obama may be riding in the wake of naming Sen. Joseph Biden as his running mate Saturday likely isn't very big, several recent polls revealed.

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A Zogby Internet poll conducted over the weekend showed Obama holding a 46 percent to 44 percent lead over Republican presidential candidate Sen. John McCain.

The most recent previous Zogby Internet poll, conducted Aug. 12-14, placed Obama's support at 44 percent to McCain's 42 percent.

Meanwhile, a Rasmussen poll released Monday showed Obama with 48 percent and McCain with 45 percent, a bump of 1 percentage point for Obama.

Another poll, this one conducted Thursday through Saturday by Gallup, saw Obama locked in a tie with McCain, with each drawing 45 percent, a total unchanged for Obama from Gallup's previous poll and a 1 percent increase for McCain.

A CNN poll conducted over the weekend also showed the presidential candidates locked in a dead heat, with each drawing 47 percent support.

That may not have been the bump Obama's campaign was hoping for and another poll conducted specifically on the issue of Biden, who chairs the Senate Foreign Relations Committee, reveals he may not have much of an impact on the race.

A new USA Today/Gallup poll released Saturday focusing on Biden showed that just 14 percent of registered voters said Biden makes them more likely to vote for Obama in November and 7 percent said it makes them less likely. Another 72 percent said he will not have much effect on their vote.

A new national poll released as the Democratic National Convention starts up revealed even more details about the race for the White House.

The ABC News-Washington Post poll says 49 percent of respondents support Obama while 43 percent prefer McCain. That lead is based largely on 20-point advantage among women voters.

But when it comes to world affairs, McCain is seen as more knowledgeable and better suited to be commander-in-chief by a margin of 2-1.

The poll was taken before the announcement of Biden as the Democratic vice-presidential candidate, but three-fourths of those surveyed said Biden's addition would make no difference to their vote.

When asked which candidate is most optimistic, those surveyed said Obama by a 2-1 margin. And the Democrat had a 50-39 lead on the question of who respondents trusted more to handle the economy.