It's not quite that simple. Mandates require a candidate to put his ideological cards on the table, so that his votes aren't votes for personalities and vague slogans. President Bush did that in this campaign and therefore has a mandate to pursue those ideological points.
On the other hand, when Presidents Reagan and Clinton were reelected, they went with warm and fuzzy slogans, so that while they had more decisive Electoral College victories, they didn't have mandates for anything more than being warm and fuzzy in their second terms.
Bush risked more ideologically, so when he won, he received a mandate.
Oh come on. Reagan's landslide victory was surely a mandate.
well put.