Liza Harvey has been elected unopposed as Opposition Leader and leader of the WA Liberal Party at a special party room meeting convened this morning.

Key points: Mike Nahan told his colleagues late yesterday afternoon he intended to quit

Mike Nahan told his colleagues late yesterday afternoon he intended to quit It followed a lengthy period of intense speculation about his leadership

It followed a lengthy period of intense speculation about his leadership Mrs Harvey becomes the first female Liberal leader in WA politics

The meeting was called after the resignation of Mike Nahan from the job on Wednesday night.

Mrs Harvey's appointment makes her the first female Liberal leader in WA.

Nedlands MP Bill Marmion has been elected deputy leader, taking over from Ms Harvey in that role.

He beat Carine MP Tony Krsticevic, who also threw his hat into the ring for the deputy position.

Bill Marmion was chosen by the party as Deputy Leader, beating MP Tony Krsticevic. ( ABC News: Benjamin Gubana )

Harvey promises new leadership style

Mrs Harvey said she would focus on holding the Government to account and the impact of government fees and charges on households.

Who is Liza Harvey? Mrs Harvey was born in Manjimup as the middle child of a family of six

Mrs Harvey was born in Manjimup as the middle child of a family of six She worked in hospitality, tourism and small business before entering politics

She worked in hospitality, tourism and small business before entering politics Her husband Hal Harvey was a well-known figure in the local angling community and died of pancreatic cancer in 2014

Her husband Hal Harvey was a well-known figure in the local angling community and died of pancreatic cancer in 2014 She has a daughter and a son, a stepdaughter and three grandchildren

She acknowledged the significance of being the first woman to take the helm of the WA state Liberal party's parliamentary team and said she would have a different leadership style to her predecessor.

"I'm really proud to be the first woman elected into that role," she said.

"My great strength that I bring to this role is my broad collective experiences that I have had while being a human being on this planet."

Liza Harvey says she and Bill Marmion will compliment each other as a leadership team. ( ABC News: James Carmody )

She denied the appointment to the deputy leadership of Mr Marmion — a party veteran who was a ministerial staffer in the Richard Court government and entered Parliament himself in 2008 — meant the party had failed to implement generational change.

"Bill has a lot of experience that he can bring to the role. And I think as a deputy backing me in, we compliment each other's experiences and talents," she said.

Before the ballot was cast, Mrs Harvey said she did not have a favourite for the deputy role and was happy to work with anyone in that position.

Mark McGowan wasted no time before taking aim at the new WA Liberal leadership. ( ABC News: James Carmody )

WA Premier Mark McGowan, who previously labelled Dr Nahan "the worst opposition leader" he had ever seen, quickly took aim at the new Liberal leaders.

"Dr Nahan has gone now and I will leave him be for today … I don't want to kick a man when he is down," he said.

"But Ms Harvey and Mr Marmion were there during the term of the Barnett government when they made a mess of Western Australia.

"It is a throwback to the worst of the Barnett government."

Harvey not told of Nahan's departure

Mrs Harvey said when pressed that she was not told of Dr Nahan's decision to resign before he revealed his decision to ABC News yesterday, and denied there was any kind of deal in place that would see him stand down halfway during his term as leader.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 3 minutes 13 seconds 3 m 13 s Mike Nahan quits as WA Opposition Leader

"After the last election we were a very bruised team, I must say," she said.

"Mike very bravely said I'm prepared to take this on for as long as you think you need me."

She said he would retain a "very important senior role going forward".

Mrs Harvey denied the leadership ballot had been rushed following Dr Nahan's resignation.

"I think if you have a look at the series of the events over the last 24 months, you would agree that nothing here has been orchestrated or designed — it has been somewhat chaotic, which is a bit regrettable," she said.

"But when you have a leader resign it is untenable to go into the next day of Parliament without having a new leadership team in place, that is why we met this morning — it had to be done."

She said she was confident the party was united behind her.

"I was elected unopposed and during the discussions around leadership nobody else was putting their name forward," Ms Harvey said.

"The entire team has backed in behind Bill and behind me."

Liza Harvey was the favourite to replace Mike Nahan after he announced he was stepping down. ( ABC News: Benjamin Gubana )

The party has chosen not to make the results of the party's leadership ballot public.

There had been days of speculation about Dr Nahan's future in the role after reports emerged he was considering standing down.

Many in the party either denied the rumours or refused to answer.

Liberal MPs were only told of the resignation last night after 6:00pm, with the news broken to the public an hour later.

Barnett's economic ghosts haunt leadership

Ms Harvey denied her leadership would be tainted by her cabinet position in the former Barnett government and its associated economic challenges.

Western Australia saw spiralling government debt and a series of budget deficits during the two-term Barnett government until its defeat in 2017.

Liza Harvey says she and her deputy, Mr Marmion, have the backing of the party. ( ABC News: James Carmody )

Ms Harvey blamed those economic outcomes on WA's low returns from the GST before a floor was set earlier this year.

"I stand proud of the achievements of the Barnett government," she said.

"We rebuilt the state, and we needed to rebuild the state to house the additional 500,000 people that came to live here during that eight years of government."

Praise from former top cop

Mrs Harvey served as police minister in the former Barnett government, but switched portfolios in opposition to focus on transport.

Former Police Commissioner Karl O'Callaghan, who worked with Ms Harvey for five years during her time as police minister, described her as a pragmatic and determined person who worked hard to win over the senior ranks of the WA Police Force.

"I think with Liza what you see is what you get," he said.

"She's very straight and I think that's what I liked about working with her, that you always knew where you stood.

"I think when you come to a position as a minister you have got to establish your credibility, but I think the senior ranks of the police force appreciate someone who is straightforward and I think that's one of Liza's strengths."