Just over two weeks from the WA Senate repeat election, the Abbott Government has lost its first minister amid a corruption probe.
Assistant treasurer Arthur Sinodinos stepped down yesterday, saying he did not want the Government's work to be distracted by a "sideshow".
But Labor has vowed to pursue the Prime Minister over the matter, with Opposition Leader Bill Shorten claiming Tony Abbott knows more about the affair than he is willing to reveal.
As well as embarrassing the Liberals ahead of the April 5 poll, Senator Sinodinos' departure from the ministry leaves a big hole in the Government's economic team seven weeks from its first Budget. Finance Minister Mathias Cormann will assume his responsibilities.
The NSW Independent Commission Against Corruption is investigating the dealings of Australian Water Holdings, which paid Senator Sinodinos $200,000 a year for working two hours a week as director and then as its chairman.
The ICAC hearing was told on Monday that Senator Sinodinos stood to pocket up to $20 million in shares from a contract between AWH and the Sydney Water Corporation and that he was employed to open doors with the Liberal Party.
In the period that Senator Sinodinos was AWH director, the company gave more than $75,000 to the NSW Liberal Party of which Senator Sinodinos was treasurer.
He has denied any knowledge of the donations.
Senator Sinodinos has said he was "shocked and disappointed" to learn of AWH's financial links with disgraced Labor powerbroker Eddie Obeid, despite Mr Obeid's son and nephew being employed by the company.
Yesterday, while Labor used Parliament to demand he explain alleged discrepancies in his story, Senator Sinodinos visited Mr Abbott to inform him he would step down.
"I do not want this sideshow to be an unnecessary distraction to the important work of the Government which I am proud to serve," Senator Sinodinos told the Senate. Mr Abbott said Senator Sinodinos, John Howard's former chief of staff, had done the "right and decent thing" in stepping aside.
He said he looked forward to Senator Sinodinos' "restoration" to the ministry but confirmed he would not draw on his ministerial salary or receive any ministerial entitlements.
Mr Shorten said Mr Abbott had failed to articulate why on Tuesday he could have full confidence in Senator Sinodinos but by yesterday was content to see him step down.