A former aide to Hillary Clinton's campaign has told CBS News that the media have been much harder on Republican vice presidential nominee Sarah Palin than the other candidates in the race, and as a result "have growing credibility problems."

In an interview posted at CBSNews.com Friday, Mark Penn eviscerated the press for "going through every single expense report that Governor Palin ever filed" whilst showing no similar interest for those of Barack Obama, Joe Biden, or even John McCain.

Readers are warned to strap themselves in tightly, for Penn spoke more plainly about media coverage of this election cycle than most in his party can tolerate (emphasis added, h/t Jennifer Rubin, photo courtesy CBSNews.com):

CBSNews.com: Your former colleague Howard Wolfson argued that you all unintentionally paved the way for Palin by exposing some of the unfair media coverage that Hillary Clinton received. And, therefore, a lot of the media may now be treating Sarah Palin with kid gloves. Do you agree with that?

Mark Penn: Well, no, I think the people themselves saw unfair media coverage of Senator Clinton. I think if you go back, the polls reflected very clearly what "Saturday Night Live" crystallized in one of their mock debates about what was happening with the press.

I think here the media is on very dangerous ground. I think that when you see them going through every single expense report that Governor Palin ever filed, if they don't do that for all four of the candidates, they're on very dangerous ground. I think the media so far has been the biggest loser in this race. And they continue to have growing credibility problems.

And I think that that's a real problem growing out of this election. The media now, all of the media — not just Fox News, that was perceived as highly partisan — but all of the media is now being viewed as partisan in one way or another. And that is an unfortunate development.

CBSNews.com: So you think the media is being uniquely tough on Palin now?

Mark Penn: Well, I think that the media is doing the kinds of stories on Palin that they're not doing on the other candidates. And that's going to subject them to people concluding that they're giving her a tougher time. Now, the media defense would be, "Yeah, we looked at these other candidates who have been in public life at an earlier time."

What happened here very clearly is that the controversy over Palin led to 37 million Americans tuning into a vice-presidential speech, something that is unprecedented, because they wanted to see for themselves. This is an election in which the voters are going to decide for themselves. The media has lost credibility with them.

Hear, hear!

—Noel Sheppard is the Associate Editor of NewsBusters. Follow him at Facebook and Twitter.