Robert Lichter–who has done surveys going back decades on the liberal inclinations of elite reporters–finds that from June 8 to July 21, 72 percent of Obama’s coverage on ABC World News Tonight, CBS Evening News, NBC Nightly News, and the first half hour of Fox Special Report was negative. Only 57 percent of McCain’s coverage was negative.

I filed a column for Time on the press’s pro-Obama bias before Lichter’s study came out. But the study doesn’t really cause me to doubt that the press prefers Obama to McCain and that this preference has affected the coverage but it does complicate the story. A story on how, say, “questions linger about Obama’s readiness to be commander-in-chief” would doubtless, and reasonably, be scored as a negative story by Lichter and company. But if that story minimizes Obama’s weakness on the issue, buys his spin on foreign policy, etc., it could still reflect bias in his favor–and that’s the type of bias that most conservative critics of the press have in mind.