The Government is trying to cut spending as economists predict it'll need to borrow billions more. 

Finance Minister Grant Robertson is cracking down on public contractors and consultants spending, announcing it'll mean savings of almost $4 billion over four years. 

Westpac Chief Economist Kelly Eckhold told Mike Hosking the Government is spending $137 billion dollars a year, but this'll help at the margins. 

He says given the revision of revenue estimates, it might need to borrow an extra $15 billion over the next four years. 

LISTEN ABOVE