You know the knee-jerk claim from conservatives when Fox News comes under attack: Partisan, Dem-cheering MSNBC is just like Fox News, except from the left, so leave Rupert's team alooooone.

Except that, of course, it's not.

Meaning, MSNBC for most of the broadcast day actually produces a straight news product, which Fox News does not. And MSNBC for the most of the day welcomes conservatives on the air to discuss the day's issues (paging Pat Buchanan!), which is a courtesy Fox News simply does not extend to liberals.

But more importantly, MSNBC tees off on Democrats, even during the channel's supposedly liberal, opinionated shows, in the way Fox News absolutely refused to do when Republicans under Bush ran Washington, D.C. (And still refuses to do today.)

For instance, I've recently made a handful of appearances on The Ed Show, and it seems like every time I'm getting mic'd up for the show, the segment before mine is taking shots at Democrats. On Monday, it was an interview with environmentalist Philippe Cousteau who faulted the White House for painting too rosy of a pictures with regards to the BP oil spill cleanup. (A critique that host Ed Schultz obviously agreed with.)

On other occasions when I've visited the set guests have belittled Democratic leadership in Congress for not doing enough to help the unemployed. And I know Schultz blamed the for administration for prematurely firing Shirely Sherrod instead of staring down that right-wing smear campaign.

And Schultz is hardly alone. Rachel Maddow spent the winter needling the administration over DADT, and Keith Olbermann recently gave Obama's primetime BP clean-up speech very low marks.

And of course that tension has been highlighted this week in the wake of WH spokesman's Robert Gibbs' disparaging comments about the “professional left” and how its criticism of Obama is so naive and out of touch. A WH aide later clarified that Gibbs was referring to “cable TV commentators.” Hmm, cable TV commentators on the “professional left?” Yeah, that would be MSNBC. And sure enough, its shows this week have been populated with guests lighting into the White House.

Here were liberal bloggers Jane Hamsher and Glenn Greenwald doing just that on MSNBC's Dylan Rattigan's show:

Bottom line: In the last four weeks, MSNBC has probably aired more substantive criticism of the current administration than Fox News aired of the Bush administration during that president's entire second term.

Period.

That's why MSNBC is not the liberal counter to Fox News. Because MSNBC does not operate as an appendage to the DNC and MSNBC does not consider itself to be a purely partisan political entity, the way Fox News now so clearly is.