Nothing is deadlier to a campaign than a rumor that a candidate might be dropping out. But NBC has seen fit to suggest that Rudy Giuliani might be withdrawing from the presidential race based on what it itself calls "speculation" in the blogosphere.

NBC Nightly News weekend anchor Lester Holt interviewed John Harwood on this evening's edition.

LESTER HOLT: Let's turn to Rudy Giuliani. He's had a health scare, he's had a drop in the polls. You've seen it in the blogosphere: a lot of speculation as to whether he'll stay in this race. What do you think?

View video here.

JOHN HARWOOD: The question arises, Lester, because of the way he left that 2000 senate race against Hillary Clinton. But I talked to his aides today. They say that he appears to be fine, he's in it for the long haul. The bigger problem may be with the voters, though. As he falls further behind in Iowa, New Hampshire, South Carolina, those early states, his lead in the bigger states to follow like Florida and California is shrinking.

The reference to "the way he left that 2000 senate race against Hillary Clinton" is an allusion to the fact that Rudy chose not to run in 2000 after he was diagnosed with prostate cancer. But if the NBC folks had tuned into ABC World News this evening, they could have viewed a George Stephanopoulos interview with Giuliani in which he said that his doctor "put out a statement that I'm in very good health; every test came back normal."

Yes, Harwood cited Giuliani campaign sources saying Rudy's in it "for the long haul." But simply floating the rumor does the damage. What are the odds NBC would give such credence to the speculation of the pajamahadeen for purposes of floating a rumor harmful to a leading Dem contender?

—Mark Finkelstein is a NewsBusters contributing editor and host of Right Angle. Contact him at mark@gunhill.net.