The Prime Minister, his agriculture minister David Littleproud, Energy Minister Angus Taylor, and the embattled former Nationals leader and special envoy on the drought, Barnaby Joyce, have all been under the pump for the better part of a week over a $79 million deal with Eastern Australia Agriculture signed off on in 2017.

The Coalition's decision to ask the Auditor-General to cast his net back to 2009 is in recognition of the fact that while Labor was in office it signed off on a separate $300 million buyback deal with the same company.

By saying all the buybacks have been referred to the Auditor-General, Mr Morrison is hoping to move the issue along until after May 18 so he and the government can concentrate on better news.

The concession is effectively meaningless given that the government has now been in caretaker mode for almost a fortnight and nobody can be sure who will be running the country in just under a month's time.

Meanwhile neither Mr Joyce, Mr Taylor, nor any other parliamentarians who may have a peripheral interest in these matters is likely to be sitting down for a tête-à-tête with staffers from the Auditor-General's office until after the booths close on polling day.

Bill Shorten, who has suggested he would back a judicial inquiry into the 2017 buyback deal, appears to be playing a dangerous game given Labor has stopped well short of supporting ongoing calls by the Greens and independents for a formal investigation into the implementation of the troubled Murray Darling Basin Plan since its inception.

The plan was developed on Labor's watch with the enabling legislation passed in 2007 and then substantially amended in 2008.

A succession of Labor figures oversaw millions of dollars of water buybacks before the 2013 election. The ALP has just as much skin in this game as the Coalition.

None of this alters the fact the Greens and the independents who are supporting them, including Kerryn Phelps, are right.

The Murray Darling Basin Authority has been mired in controversy almost from the start with its then chair, Mike Taylor, resigning in January 2011 citing concerns the plan was compromised and would not return enough water to the basin.

Four months later the Wentworth Group of Concerned Scientists, who had initially backed the authority and the plan, withdrew their support on the grounds the process was seriously flawed and a waste of taxpayers' money.

They may well have been onto something given that in the years since then an estimated $8.5 billion has been spent to little or no discernible effect.

Water flows have not increased, there have been record fish kills and water monitoring at key hydrologic indicator sites has been abandoned due to funding cuts.

Meanwhile the Morrison government wants to relocate 76 Murray Darling Basin Authority jobs from Canberra to Murray Bridge and other regional sites, a move critics say will rob the ACT office of policy expertise and disrupt vital work.

It is, in short, a classic political football.

An "access-all-areas" and "ask-any-question" style review is the only way taxpayers will ever know if their money has been managed prudently.

Such a review is now well and truly overdue.