Vice President Cheney said that Bush had run on a clear agenda and that “the nation resounded by giving him a mandate.” Source: WP

Main Entry: man·date
Pronunciation: ‘man-“dAt
Function: noun
Etymology: Latin mandatum, from neuter of mandatus, past participle of mandare to entrust, enjoin, probably irregularly from manus hand + -dere to put
1 a : a formal communication from a reviewing court notifying the court below of its judgment and directing the lower court to act accordingly b : MANDAMUS
2 in the civil law of Louisiana : an act by which a person gives another person the power to transact for him or her one or several affairs
3 a : an authoritative command : a clear authorization or direction b : the authorization to act given by a constituency to its elected representative

Source: Merriam-Webster Dictionary of Law, © 1996 Merriam-Webster, Inc.

So indeed, a majority vote does give Bush a mandate, under definition 3b:, except that the President is not an elected Representative, especially of the constituency of American Voters. Representatives are in Congress.

But I think most people think of ‘mandate’ in terms of 3 a : an authoritative command : a clear authorization or direction. I don’t see where a 51-48 edge between some rather conflicting philosophies provides any clear authorization or direction. Of course, Bush does not need a mandate from the electorate since he has one from a higher power…