Ferguson was the seventh casualty of the toxic leadership spill that rocked the federal parliament on Thursday.

There was an almost immediate outpouring of good wishes for the departing minister from key resources lobby groups. Ferguson had been considered a solid minister who understood the industry.

Gray has been touted as the front-runner for the role. He certainly has understanding of the resources industry, being a key Woodside executive with responsibility for government relations.

He has also has shown his understanding of the industry by helping Gina Rinehart secure 457 visas for an iron ore project.

There are, however, concerns that his time at Woodside means that he is still too close to the industry.

Smith has proved himself to be a very safe pair of hands. He was cruelly, many believe, tipped out of the foreign minister’s seat after the 2010 leadership coup that made Julia Gillard Prime Minister and has been considered a good defence minister.

However, there is a belief that the defence portfolio needs some continuity and that Smith would be better served retaining it.

Regardless, the farcical leadership spill has proved extremely costly to a government that is showing all the signs of being on its way to a monumental defeat in the September election.

The loss of Ferguson will not help its cause.

The former resources minister called a press conference to announce his departure from the office, based on his decision to back Kevin Rudd as leader of the Labor party.

According to ABC News, he regarded it as “the only honourable thing to do” in light of his decision to support the former prime minister, who then said he would not challenge.

Ferguson held the position since 2007 under the Rudd government.

His loss could provide some discord on a portfolio that both sides of politics had seemed to view similarly.

Ferguson oversaw the controversial carbon tax and had a clear view in favour of carbon pricing.

He also slammed the New South Wales government for its back-flip on CSG exploration and said the government needed proper consultation with industry before making knee-jerk decisions.

Minerals Council of Australia acting chief executive officer John Kunkel said Ferguson had a deep understanding of the mining industry and a strong commitment to consult it on policy challenges.

“He understood the need for Australia's mining industry to remain competitive in global markets,” Kunkel said.

“He recognised that Australia's status as a premier mining country is not preordained by our resource endowment. And as his remarks today demonstrated, he grasped that effective government is primarily about providing a framework for long-term growth and prosperity, not about fomenting conflict and class war.

“It is no secret the mining industry has at times been sharply critical of the direction of government policy in recent years. The MCA continues to make the case for reform that will deliver improved productivity and cost competitiveness.

“Yet at all times the industry has held Martin Ferguson in high regard based on his knowledge, his integrity and his preparedness to deal in an open and straightforward way with the industry.

Ferguson said he would run in the September election and support his party from the backbench.

He joins Simon Crean, Chris Bowen, Joel Fitzgibbon, Richard Marles, Ed Husic and Janelle Saffin.

Just an hour after Ferguson’s announcement, human services minister Kim Carr also announced his decision to step down.

Party elder Simon Crean called for a spill Thursday morning before question time, calling on Kevin Rudd to put himself forward for prime minister.

Crean called it a “risk worth taking” to end the party squabbling, stating he wanted to give Labor a fresh start.

Rudd chose not to stand and Gillard and Swan were re-elected unopposed.