The federal government’s $17.9 billion infrastructure splurge is tilted towards Coalition-held seats and marginal electorates Scott Morrison must hold at the May election, with almost 40 per cent of NSW’s funding allocated to one must-win electorate.

Some marginal electorates have received a disproportionate share of funding in the pre-election spending spree, with voters in the must-win seats of Boothby in South Australia and Dobell in NSW offered billions in road and rail upgrades.