PRIME Minister Scott Morrison has promised to deliver the multibillion-dollar GST fix as he spoke of his admiration for the people of WA.

In his first interview since ascending to the nation’s top job, Mr Morrison told The Sunday Times his “commitment to delivering a fair outcome on GST for WA remains firm”.

Before he was dumped dramatically by his Liberal colleagues this week, former PM Malcolm Turnbull pledged his government would deliver WA $4.7 billion in extra GST cash over eight years. “My commitment to delivering a fair outcome on GST for Western Australia remains firm,” Mr Morrison, Australia’s 30th prime minister, said of the most contentious political issue on the west coast.

“We understood Western Australians were concerned they were not getting their fair share. And they were right to feel short-changed, particularly given economic growth in WA had been a significant driver of our nation’s prosperity.

“As treasurer, I took time to understand the problem and find a solution. The plan we have put forward to address the imbalance in GST funding is a sensible, practical and fair solution to the problem. And it finally ensures WA gets the fair share that it deserves.”

The changes, which would also see the introduction of a 75¢ floor, were thrown into doubt this week when Queenslander Peter Dutton emerged as the frontrunner to replace Mr Turnbull.

But the 50-year-old father-of- two — a devout Christian and keen rugby league fan — said his Liberal colleagues in the west, “led by Mathias Cormann, remain tireless advocates on this issue”.

“As a bloke from a place called the Shire over east, full of families and small businesses, I have always admired the enterprising spirit of those who have built WA to the great State it is today,” Mr Morrison said.

“Many think of mining when they think of WA, I think of the people who are working hard for their families be it in mining, agriculture, defence or the terrific education, science and technology sector the west is growing.

“This has reinforced for me the importance of our guiding value of a fair go for those who have a go.”

On Friday night Mr Morrison was meant to be at home to cook a curry for wife Jenny and his two girls, Lily and Abbey. Instead Australia’s newest PM has spent the past 48 hours in briefings with army chiefs and taking calls from world leaders.

It’s a big change for Mr Morrison and Jenny, whom he met through church connections when they were both teenagers, marrying at 21. Mr Morrison spoke to Australia’s new first lady in the moment before he entered Friday’s ballot.

“I said, ‘You are always here at the end of the day, and that’s what matters most’,” Mr Morrison said. “It’s a pretty significant moment. I would have wanted Jen and the girls here either way.”

Playing in his office yesterday afternoon, daughters Lily, nine, and Abbey, 11, seemed oblivious to the change their family has seen. “They are young girls and Jenny and I obviously want to be very careful of that,” Mr Morrison said.

He hasn’t ruled out moving his family to Canberra.

“This is a big change ... but we make these commitments as a family. At the moment we will stay in the Shire. It’s pretty hard to pull people out of the Shire, it doesn’t matter whether you are nine or 50,” he said.

“One of the things the girls said to me this morning, they said ‘Does this mean you’ll be speaking to Mr Trump?’ I said ‘Yes it will, darling’.”

Of his first call with the US President yesterday, the PM said: “I did tell him I was a rubbish golfer. I am not quite sure that term is well known in the US so there are other phrases I have and I’ll have to be careful of using Shire-colloquialisms in international engagements.”

Mr Morrison said he would be a “fresh and optimistic” PM and admitted his party must heal but vowed to fight Opposition leader Bill Shorten on fairness.

“Fairness means many different things to many different people but to me it means that if you have a go, you’ll get a go,” he said. “That’s what we bring to the world, that optimistic attitude where everyone can have a go. A fair go doesn’t mean everybody gets the same things, a fair go assumes you are going to have that go.”

He believes his rise to the top alongside deputy Josh Frydenberg signals a generational change for the Liberal Party.

“The circumstance in which Josh and I have come into the leadership are quite unique in modern political times in Australia,” he said.

“We have both stepped up to these roles having been very supportive of the prime minister and Julie (Bishop, the former deputy leader).

“We have crossed that bridge yesterday (Friday). It wasn’t a bridge we all necessarily wanted to cross at the start of the week.”

Mr Morrison will next week visit drought-stricken Queensland.