Dean Nalder will challenge West Australian Premier Colin Barnett for the Liberal party leadership if a spill motion is put forward this week but says he will not instigate it.
"If the party room does put a spill motion on Tuesday, I will nominate for the position of leader," Mr Nalder told reporters on Sunday.
He quit as minister for transport and agriculture this weekend ahead of the March election and said while he had never done the numbers, there were people who privately supported him and were pushing for a leadership change.
The premier has also ruled out launching a spill motion to settle speculation about his leadership, saying he does not play games, but intends to remain in the role.
Mr Nalder said he left a message for the premier about 7.30pm on Saturday regarding his resignation, but never received a call back and had to contact Mr Barnett's chief of staff.
Mr Barnett, who marks eight years as premier this week, fronted the media with his wife and said he received a message from Mr Nalder at 10.30pm.
He said Tony Simpson, who quit earlier in the day as local government minister and told reporters the state government had lost its way, never mentioned any leadership concerns to him.
"I am extremely disappointed in both Tony Simpson and Dean Nalder that they did not have the courage or integrity to tell me of their decision face to face or even on the telephone," Mr Barnett said.
"There is something orchestrated about this."
The premier said he had given Mr Nalder, who had only been a minister for a little more than two years, a great opportunity with important portfolios but he walked away from it.
"I had shown great faith and confidence in Dean and he let me down," he said.
The premier said Mr Nalder had assured him he was not involved in a recent poll organised by businesspeople that was "clearly designed to topple" Mr Barnett, but said he now had some doubts about that.
Mr Nalder denied he and Mr Simpson quit as part of an orchestrated campaign against Mr Barnett and said he took offence to the premier saying he failed to show integrity.
Mr Nalder said it took him six months to get a one-on-one meeting with Mr Barnett and criticised the premier's lack of consultation and refusal to support his plan for the Perth Freight Link.
Both he and Mr Simpson have said they learned about policy positions through the premier's speeches or talkback radio appearances.
But Mr Barnett said there were regular cabinet meetings, although he sometimes made a call if a minister was not progressing issues quickly enough.
"I do become a little bit intolerant when issues are allowed to drift," he said.
Mr Barnett said while people labelled him arrogant and "the emperor", he thought of himself as decisive.
Deputy Premier Liza Harvey reiterated her support for the premier, saying there was only a small number of disaffected and disgruntled agitators, but the majority of the parliamentary team still backed him.
She also disagreed that Mr Barnett lacked consultation with ministers.
It comes as a ReachTel poll of 1724 people was published in The West Australian putting Labor ahead 51-49 on a two-party preferred basis, which is closer than previous polls.
Labor stalwart Alannah MacTiernan said the Liberal party was falling apart, while leader Mark McGowan said the government was fighting with itself and had lost the right to govern.
