The Opposition is questioning what could result from Premier Colin Barnett's decision to appoint an economic hardliner as Western Australia's incoming treasurer.

Mr Barnett announced Mike Nahan would take on the role on Friday, days after the resignation of Troy Buswell from Cabinet following an incident in which he crashed his ministerial car.

Dr Nahan is the former head of a right-wing think tank and has written numerous articles in favour of privatisation.

In 2005 he wrote an opinion piece in which he said the Perth to Mandurah rail line and the state's first desalination plant "will be monuments to waste".

Mr Barnett has already said he will take charge of any planned asset sales.

Opposition treasury spokesman Ben Wyatt says Dr Nahan's pro-privatisation views are in contrast to those of Mr Barnett.

"Ultimately I daresay Mike Nahan would embarrass [Barnett] in some of his intentions in respect of asset sales, so Colin Barnett is going to keep a very close watch on Mike Nahan in light of his somewhat right-wing, strange views on the role of government in the past," he said.

"What strikes me about Mike Nahan is a huge hostility to the taxpayer funding public transport, the taxpayer funding water desalination plants, a huge hostility to people who may be on social welfare for some reason or another."

However, Mr Barnett said Dr Nahan will be a "forensic" treasurer and denies his Cabinet will see the Government lurch further to the right economically.

"Mike Nahan has proven an excellent member of Cabinet and has impressed me with his ability to work through complex financial and logistical matters in the Energy and Finance portfolios over the past year," he said.

Tight budget another issue, business commentator says

Business commentator Tim Treadgold says he expects Dr Nahan and Mr Barnett to be at loggerheads over some key issues.

"Colin Barnett would like to use secateurs and Mike Nahan would like to use shears to take whole chunks of the tree off," Mr Treadgold said.

"That's going to lead to tensions in government."

He said another problem for Mr Nahan is a shrinking budget.

"We had a big event in the finance market last week and that was the collapse of iron ore prices," he said.

"I think it would be interesting to speak to Treasury to see what effect that's had on their budget planning because it will have knocked a very large hole in the state budget."

But Mr Barnett has played down the differences.

"I've been in politics for a long time so I guess I've had maybe more time balancing out philosophical positions with the practical reality of running a government," he said.