Former federal MP Stephen Smith has confirmed he will try to topple WA Labor leader Mark McGowan if asked to do so by the party, but some caucus members are highly critical of the "destabilising" proposal.

Key points: Stephen Smith says he is prepared to take on Labor leadership in WA, if asked

Stephen Smith says he is prepared to take on Labor leadership in WA, if asked Apparently approached by MPs fearing Mr McGowan not up to task

Apparently approached by MPs fearing Mr McGowan not up to task Some state MPs worry leadership spill will destabilise party

As revealed by the ABC on Thursday, part of the Labor caucus wants Mr Smith to lead the party to the 2017 election, replacing Mr McGowan.

Mr Smith has not returned the ABC's calls but has now told a Perth newspaper he is up for the top job.

It would not be the first time a state Labor leader has been challenged: in 1990 premier Peter Dowding was replaced by Carmen Lawrence, aided by the then state secretary Mr Smith.

But Labor's leader in the WA Upper House Sue Ellery said Mr Smith did not have the majority support of caucus.

"Stephen is saying he's ready if asked. We are not asking, there is not a majority, in fact the majority of caucus is horrified by the events of the last few days," she said.

"Stephen was a part of a government that was racked by and eventually destroyed by leadership destabilisation and WA voters, in fact, emphatically rejected that.

Who is Stephen Smith? Born in Narrogin, WA, in 1955 and spent early years there and Southern Cross

Born in Narrogin, WA, in 1955 and spent early years there and Southern Cross Educated at Christian Brothers High School in Perth

Educated at Christian Brothers High School in Perth Holds Bachelor of Laws at University of Western Australia, Masters from London University

Holds Bachelor of Laws at University of Western Australia, Masters from London University Worked as a solicitor and barrister in Perth, lectured and tutored law in London

Worked as a solicitor and barrister in Perth, lectured and tutored law in London State secretary of WA Labor from 1987 to 1990

State secretary of WA Labor from 1987 to 1990 Special advisor to Bob Hawke and senior advisor to Paul Keating 1991 to 1992

Special advisor to Bob Hawke and senior advisor to Paul Keating 1991 to 1992 Elected to the seat of Perth in 1993 and held it for two decades

Elected to the seat of Perth in 1993 and held it for two decades Held shadow portfolios including trade, resources and energy, industry, infrastructure, industrial relations, immigration and communications

Held shadow portfolios including trade, resources and energy, industry, infrastructure, industrial relations, immigration and communications Held foreign affairs and defence portfolios while Labor was in government

Held foreign affairs and defence portfolios while Labor was in government Married with two children, lives in Perth

"Mark McGowan has the overwhelming support of the overwhelming majority of the state Labor caucus, there is not a shadow of a doubt about that. Stephen Smith does not have a majority in caucus."

WA's shadow treasurer Ben Wyatt said he was mystified by Mr Smith's plan.

"I don't know what the plan is, Stephen says he's ready to lead, well he's the number 33rd in line, the first 32 of which are in the WA Labor caucus," he said.

"The fact that this isn't a plan with a coherent strategy simply means this will just create uncertainty and division in the Labor Party, and that's something I fear will distract us from our prime task of bringing down the Barnett Government."

Federal Opposition Leader Bill Shorten refused to be drawn on the west coast spat, saying he expected WA Labor to "sort this matter out quickly".

When asked what kind of leader Mr Smith would be, Mr Shorten refused to back one man over the other.

"I think Stephen Smith had a distinguished career in federal politics. Mark McGowan has been doing a good job in terms of his opposition role," he said.

"I'm simply not buying into it. Labor voters across Australia expect us to be united. They expect me to focus on the issues which affect millions of Australians."

McGowan 'deserves support of caucus'

Mr Wyatt supports Mr McGowan for leadership but would not comment on who might be opposing the current leader.

"I'm not going to speculate on that ... this is a plan I can't see going anywhere other than into destabilisation," he said.

"Mark's shown over what has been a number of years now ... [that] he deserves the support of the caucus.

"Importantly for Mark, he's in the caucus and ultimately this is what mystifies me about the plan for Stephen Smith to lead."

Mr Smith and Mr McGowan have been contacted for comment.

Mr McGowan said on Saturday he did not want the "Canberra disease" of leadership speculation exported to WA, and that he had majority support of MPs.

He said he understood just "three or four" MPs were not supporting him, and claimed to have the support of "90 per cent of his colleagues".

He has faced criticism from former WA Labor state secretary John Halden, who claimed he was not "flamboyant" enough for the role.

Mr Smith was foreign affairs minister under Kevin Rudd's government, but after the 2010 election that followed the much-publicised leadership spill by Julia Gillard, he took over the defence portfolio, making room for Mr Rudd to pick up foreign affairs.

The veteran MP was the federal member for Perth from 1993 up to 2013, announcing he would stand down at the election following Mr Rudd's toppling of Ms Gillard in mid 2013.