From the day Mike Nahan was anointed the man to lead the WA Liberal Party out of the ashes of a catastrophic 2017 election defeat, he never really stood a chance.

Dr Nahan was viewed as a long shot to take on the leadership in the moments after Colin Barnett's government was turfed from office, but he ended up taking on the top job unopposed after every other aspirant decided not to run.

The decision to fill that leadership vacuum earned Dr Nahan praise from even some of his harshest external critics, but winning over MPs in his own party proved a far more difficult task.

Leadership speculation swirled around Dr Nahan from the day he took on the top job. ( ABC News: Jacob Kagi )

Leadership speculation raged from the day the American-born MP took the job, with plenty of Liberals and media commentators viewing him as a chair-warmer rather than a realistic alternative premier.

Questions about his future in the role turned into an almost-weekly circus at State Parliament, virtually destroying any chance Dr Nahan had of enjoying enough clear air to take the challenge to the McGowan Government.

Even electoral success, such as winning back Darling Range off Labor at a 2018 by-election and the Liberals' dominant WA showing in the May Federal Election, did little to ease the internal criticism of Dr Nahan.

Critics both inside and outside the party argued that his opposition had failed to land any punches against the Government, pointing to performances in Parliament that were widely considered lacklustre and what some saw as an inability to prosecute arguments of Labor's faults.

Own goals, such as the emergence of a feud with the state's daily newspaper and the admission of a long-running tax stoush with the US Government, did not help that cause.

He was also regularly compared in an unflattering manner to The Simpsons' character Ned Flanders, through his accent, appearance and mannerisms.

The West Australian launched an attack on Mike Nahan after he questioned its influence. ( ABC News )

There was also a fear in some quarters that Dr Nahan, as the treasurer who handed down the budgets containing record multi-billion-dollar deficits and surging state debt, was too close to the baggage of the former Barnett government.

Ultimately Dr Nahan's tenure ended on what he insisted were his own terms, saying he had achieved everything he set out to and the party was best served by someone else leading it to the 2021 election.

But even had he wanted to stick around, many Liberals and most of their opponents concede those hurdles would have been too much for Dr Nahan to overcome.

A remarkable rise stopped short of the top job

But one issue not up for debate is the remarkability of one of 13 children, raised on a self-described "dysfunctional hobby farm in the backblocks of Michigan", emerging to be a senior politician in Western Australia.

Dr Nahan rose through the ranks of the WA Liberals to take charge of the state's finances. ( ABC News: Andrew O'Connor )

He settled in WA aged 32, saying he chose Australia "knowing what the rest of the world had to offer", and devoted his life at that stage to academia.

He most notably served as a prominent free-marketeer with conservative think tank the Institute of Public Affairs, before entering politics through winning the ultra-marginal seat of Riverton for the Liberals in 2008.

That victory propelled the conservatives back into government and Dr Nahan did not have to wait for long on the backbench, earning his way into the ministry in 2013.

An even bigger promotion came in 2014 when he was put in charge of state finances as treasurer.

Appointed Treasurer by Colin Barnett in 2014, Dr Nahan couldn't stop an economic crash. ( AAP: Angie Raphael )

In that role, Dr Nahan proved a passionate fiscal conservative, but struggled to rein in the big-spending approach of Mr Barnett as the state battled to keep pace with dramatic population growth at the peak of the mining construction boom.

He clamped down hard on public sector growth and pay increases while pushing Mr Barnett agree to put Western Power up for sale.

But that proved nowhere near enough to stop an alarming slide in the state's financial position, with multi-billion deficits he described as "screamers", state debt surging past $30 billion and credit rating downgrades all plaguing his tenure.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 51 seconds 1 m 51 s How WA went from boom to bust

Dr Nahan's prospects of earning an even higher position in a state nearly 20,000 kilometres from where he grow up will not come to fruition, now he has decided to walk away.

Critics will argue Dr Nahan's performance as opposition leader made that an inevitability.

But supporters will have their share of evidence to argue that, despite his intellect and economic expertise, he never stood a chance — even if he had wanted to.