Mike Nahan has been voted in unopposed as leader of the WA Liberals after two-term premier Colin Barnett stepped down following the party's crushing election defeat.
While Mr Barnett had long said he wouldn't have served a third term in full and recently admitted he suffered a mystery blood disorder last year, Dr Nahan, who is also 66, said he was healthy and in it for the long haul.
He had no competition, given former corrective services minister Joe Francis lost his seat along with six other cabinet members, and Liza Harvey decided to remain deputy leader.
The Liberals now hold just 13 seats in the 59-seat parliament, a result Dr Nahan described as shocking and disappointing.
But the straight-talking, Michigan-born former state treasurer says it's time for the party to gird its loins and try to cut short Labor's reign after just one term.
He said it wasn't impossible for the Liberals to achieve a swing of 7.3 per cent and seize back power at the 2021 state election - assuming their damaged relationship with the Nationals can be repaired for another coalition.
"We can come back and that's my task," he told reporters on Tuesday.
"I'm confident we can do that."
He insisted his small team was unified and had learnt harsh lessons from its punishment at the polls.
Dr Nahan would not be drawn on whether Mr Barnett had taken blame for the devastating election loss, but said there was no doubt he would depart the back bench, triggering a by-election for his seat of Cottesloe.
While Dr Nahan said just days ago he'd prefer Mr Barnett leave sooner rather than later, he now says his former leader will choose when to retire.
Dr Nahan recently admitted he and some of his colleagues believed Mr Barnett should have stepped aside in September when a leadership spill failed to get off the ground.
Liberal upper house MP Robyn McSweeney, who was dumped as a minister after the 2013 election and was among 15 of Mr Barnett's colleagues to vote in favour of the ultimately defeated spill attempt last year, said she felt he was burnt out.
"I think he should go and let people get on with it," she told journalists.
"The Liberals will have a hard road ahead of them.
"Out with the old and in with the new."
Mr Barnett was known for his autocratic style, earning him the title The Emperor, but Dr Nahan said he'd have a consultative approach, acting as a team leader, not a boss.
He said the Liberals would be aggressive in opposition, however.
As Mr Barnett entered parliament for the last time as leader before the party vote, he told reporters he appreciated many messages from across the state respectfully wishing him well and repeated he would "go quietly" to the back bench.
