WA Nationals leader Brendon Grylls appears set to pay a heavy price for his proposed mining tax, with the latest count showing him likely to lose his seat, and deputy Mia Davies not ruling out taking over the reins.

Key points: Brendon Grylls entered the election with an 11.5 per cent margin in his seat of Pilbara

Brendon Grylls entered the election with an 11.5 per cent margin in his seat of Pilbara He trails his Labor rival by 350 votes and may not be able to bridge the gap

He trails his Labor rival by 350 votes and may not be able to bridge the gap Labor could beat Liberals in Jandakot, Joondalup, Kingsley, Murray-Wellington

The northern WA electorate is one of seven still in doubt after Labor's landslide victory in Saturday's West Australian state election.

Mr Grylls faced a massive advertising and publicity campaign from the mining lobby, which spent more than $2 million trying to convince voters to abandon the Nationals and kill off the tax.

Mr Grylls won the traditionally Labor seat of Pilbara in 2013, ironically on the back of the massive anti-Labor backlash against the federal mining tax proposed by Kevin Rudd and Julia Gillard.

He held the seat with an 11.5 per cent margin, but is now trailing Labor's Kevin Michel by 237 votes.

ABC election analyst Antony Green said that Labor lead would be extended by another 120 votes with the inclusion of preference votes from special hospital and remotes booths.

"So Brendon Grylls is more than 350 votes behind, and I think its going to be very difficult for him to turn that lead around," Mr Green said.

Postal votes are yet to be counted, but past trends suggest they will not be enough to bridge the gap.

"So it may be that Brendon Grylls is facing defeat at this election," Mr Green said.

Davies, Redman among possible leadership contenders

Deputy leader Ms Davies said while it was too early to discuss a change of leadership, she would not rule out contesting should Mr Grylls lose his seat.

"They are conversations for the party," she said.

"I'm not going to be canvassing any of those things in the next few days."

Terry Redman, who led the party from 2013 before he was ousted by Mr Grylls in August, would not be drawn on whether he would recontest.

"There's a lot of things that happen before we get to decisions like that," he said.

"If you go back four years I myself was telling the media I had lost my seat."

Tense few days for Francis

Meanwhile, Liberal Corrective Services Minister Joe Francis' seat of Jandakot is on a knife-edge, despite having been one of the Liberals' safest electorates prior to the election with a margin of 18.3 per cent.

Joe Francis has declared his interest in the Liberal leadership but must first retain Jandakot. ( ABC News: Andrew O'Connor )

Mr Francis trails Labor's Yaz Mubarakai by 26 votes but is likely to close that lead with postal and pre-poll votes, with the result set to rest on absent votes.

"It's very difficult to estimate who the absent votes will favour," Mr Green said.

"It's a radically redrawn electorate ... so it's very hard to tell but he'll have a couple of days of waiting to see.

"Joe Francis seems to have hopes of seeking the Liberal Party leadership, but he's got to survive the next week and actually win his seat first."

Liberals seek Kalgoorlie respite

Elsewhere, the outcome in the Goldfields seat of Kalgoorlie remains wide open, with the Liberal, National and Labor candidates all sitting on primary votes of between 25 and 27 per cent.

One Nation secured 11.7 per cent of the primary vote.

Mr Green said the outcome would rest on the preference distribution, and that would be determined by which order the parties finished on their primary vote.

But he said it looked like a Liberal gain.

"Whichever way it finishes, the Liberals should be able to defeat whoever finishes second, so that looks like the Nationals have lost the seat to the Liberals there," he said.

In Perth's northern suburbs, Mr Green said he expected Labor to win Joondalup, with Emily Hamilson ahead of Liberal Jan Norberger.

Liberal Mental Health Minister Andrea Mitchell remains under threat in Kingsley, where she trails Labor's Jessica Stojkowski by more than 300 votes.

Liberal backbencher Murray Cowper appears likely to lose his seat of Murray-Wellington to Labor's Robyn Clarke, who is ahead by more than 400 votes.

However the Liberals look set to retain Geraldton, where Ian Blayney leads Labor's Lara Dalton by 278 votes and where postal votes are expected to help him maintain that buffer.

Vote counting and checking is due to resume at 9:30am.