Is CNN Shilling for Kerry?

Don't know for sure, but if not, can someone please explain to me this sequence of two sentences?

Fifty-one percent of likely voters said they would back Bush,
and 46 percent expressed support for Kerry.

The margin of error was plus or minus 3 percentage points, meaning the true
leader was unclear.

I never did advance beyond AP Calculus, but doesn't 5 less 3 make 2? And wouldn't that make Bush the "clear" leader according to this poll?

No, and I am a dufus for suggesting it (yesterday) because I fell for the so-called problem of "innumeracy." My thanks to those who pointed it out. The margin of error applies not to the differential between the candidates, but rather to the percentage of support each candidate receives. So CNN, of course, is correct in its analysis. Here's a useful article explaining this phenomenon.