Poll of polls: Obama's national lead triples

[cnn-photo-caption image= http://i.cdn.turner.com/cnn/2008/images/04/16/art.clinton.obama.jpg caption="Obama expands lead nationally according the the latest CNN poll of polls."]
(CNN) - Barack Obama has extended his lead in national polls over Hillary Clinton, despite several days of negative coverage over his controversial comments about some small-town Americans.

According to a new CNN analysis of several recent polls, the Illinois senator now holds a 9-point lead over Clinton, 50 percent to 41 percent. That compares to the 3-point margin Obama held over Clinton at the end of March.

The so-called "poll of polls" includes surveys conducted between April 7-15 - meaning four of the days were those that immediately followed the initial reports of Obama's now-famous comments.

The polls included in the analysis were those conducted by Gallup, ABC/Washington Post, Reuters/Zogby, and AP/Ipsos.