A key ally of Tony Abbott has criticised Prime Minister Malcolm Turnbull's timid approach to workplace reform and failure to flesh out his "jobs and growth" election mantra with actual substance.

With tensions between Mr Abbott and Mr Turnbull already running high after their public spat over gun control and their showdown over Liberal Party reform, former workplace relations minister and Abbott lieutenant Eric Abetz has thrown more fuel on the fire.

In a speech to the conservative H.R. Nicholls Society in Melbourne on Friday night Senator Abetz was deeply critical of Mr Turnbull's election campaign, which left the Coalition with a one-seat majority.

With Opposition Leader Bill Shorten's union links in the frame after the Royal Commission into union corruption, Senator Abetz said he had expected the Coalition to campaign on the "vital importance" of resurrecting the Australian Building and Construction Commission - the very issue Mr Turnbull used to trigger the July 2 double dissolution.