It's ridiculous to even mention the word mandate with a squeaker (sp?) election like this. 51% does not mean a mandate. 70% or 80% means that the electorate is behind you, and thus you should vigorously pursue your agenda. 51% means that half the electorate rejected the agenda.
Maybe the fact that people even *consider* this narrow victory a mandate is a product of our winner-take-all political system, and a switch to proportional representation in multi-member districts for the legislature would introduce a more reasonable way of thinking.