The overriding reason that the ALP federal government is so committed to a balanced budget is to obviate the fact that it is 1989 since a federal ALP government has delivered a balanced budget.

Keating walked out leaving an accumulated national deficit of 86 billion (10 billion more than he admitted previous to the election) and it took Howard and Costello a decade to wipe the slate clean.

Gillard and Swan are terrified of facing another election without having delivered a surplus budget.
To face another election without delivering a surplus budget since 1989 would be a bridge too far for the ALP.