(CNN) - Barack Obama is holding onto a slim edge over John McCain, the latest CNN Poll of Polls suggests.
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After several days of tough new ads from McCain’s campaign, the presumptive Democratic nominee holds a 4-point advantage over the presumptive Republican nominee in CNN's average of national polls, up slightly from the 3-point margin he held on Friday.
A week ago, he led McCain by a six-point margin, a reflection of traditionally volatile summer polling.
The poll of polls includes the latest Gallup daily tracking poll, conducted August 2-4, that gave Obama a 4-point advantage. Late last week, the same poll showed the two candidates tied at 44 percent.
“The Democrats appear to have blunted any momentum Sen. McCain gained from last week’s ad associating Sen. Obama with Britney Spears and Paris Hilton,” noted CNN Senior Political Researcher Alan Silverleib. “Once again, we are seeing that Obama has a small but durable edge over McCain. It is up to McCain to find a way to change the fundamental dynamics of this campaign.”
In addition to the Gallup daily tracking poll, the CNN poll of polls also included a USA Today/Gallup survey conducted July 25-27 and a CNN/Opinion Research Corporation conducted July 27-29. The CNN poll of polls does not have a margin of error.