Media Matters has, on more than one occasion, documented the extent to which Sunday morning shows rely heavily on Republican guests. This week, Roll Call took a crack at it, referencing its own database of lawmakers’ television appearances.

Not surprisingly, Roll Call found, “If you were watching the major Sunday morning talk shows last year, your odds of seeing a Republican Member of Congress in the guest chair were far greater than seeing a Democratic Member of Congress.”

In 2009 and 2010, Republican Members held a small advantage over Democratic Members in appearances on these programs, getting 52 percent of the invites in both years. […]

But in 2011, the GOP lawmakers captured 64 percent of the Congressional appearances on the five shows that Roll Call tracks, and every network featured more Republican lawmakers than Democrats. Of 330 Congressional appearances tallied by Roll Call last year, 210 went to Republicans and only 120 went to Democrats — fewer if you subtract the eight appearances made by Sen. Joe Lieberman, a Connecticut Independent who caucuses with Democrats.

A 210 to 120 margin isn’t exactly close.

The Roll Call piece quoted Michael Shanahan, assistant director of the George Washington University School of Media and Public Affairs, saying the gap is understandable in light of the 2010 midterm results and the dramatic debates of 2011. “Really, who were the actors in this drama? Republicans,” Shanahan said.

That’s not a bad explanation, I suppose, but it doesn’t quite work for me. If the media turned to Republican officials more in 2011 because of various disputes dictated by the GOP, what explains the media also relying on Republicans officials in 2009 and 2010 — when there was a Democratic White House, Democratic Senate, and Democratic House?

For that matter, what explains the fact that the same dynamic has existed for many years, with the Sunday shows always relying on more GOP guests?

The answer, I suspect, has a lot to do with what Josh Marshall described many years ago as the way in which the political establishment is “wired’ for Republicans — major outlets routinely place more importance on GOP opinions and perspectives, so it stands to reason they’ll invite more GOP officials on to the Sunday shows.

Something to keep in mind the next time someone complains about the “liberal” media.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.