In my limited understanding of the two terms, it would be both: when Dingy Harry said it, it was slander; because it is printed in the Congressional Record as a result of his speech, it could be libel.
Of course, any such suit could end up in the court of a liberal Clinton appointed judge, and that--as they say--is that. I'm not a lawyer, but just based on the surface meaning of the words, it would be BOTH slander and libel.
I'd like to see the Republicans initiate an ethics investigation of Reid's behavior. They have the right and power to do so, and IMO they have a case for sanction. Hell, every time Trent Lott farted the Dims were demanding an investigation. Let's stick it to them for a change.