The Barnett Government has ruled out any pause to the clearing of bushland for the Roe Highway extension in Perth, despite Labor's pledge to scrap the project if it wins the March state election.

The Government remains embroiled in a bitter dispute over the $450 million Roe 8 extension to Stock Road across the Beeliar Wetlands, where construction contractors are facing daily protests.

It is clearing almost 100 hectares of bushland despite WA Labor's pledge to scrap Roe 8 and the Perth Freight Link project if it wins office in March, and a succession of failed legal efforts by the group Save Beeliar Wetlands to block the project.

Albert Jacob is untroubled by the prospect of clearing land for a project that may be stopped. ( ABC News: Andrew O'Connor )

Labor and opponents of the project have repeatedly urged the Government to cease work until after the election, but their calls have been ignored.

Environment Minister Albert Jacob was untroubled by the possibility that 97.8 hectares of land may be cleared for Roe 8 by election day, only for a newly elected Labor government to cancel the project.

"I am comfortable with that clearing. This project has been through an extensive environmental approvals process, that clearing is happening in an existing road reserve, that area has been a road reserve for decades," he said.

"Government is difficult. Government timelines are difficult. This project is already significantly delayed.

"This was our commitment, so we are delivering it. I think governments are expected to deliver their commitments."

There have been ongoing protests against the Roe 8 highway extension. ( ABC 720 Perth: Alex Hyman )

Opposition transport spokeswoman Rita Saffioti said she was stunned Mr Jacob would support clearing land for a project that may not proceed.

"It's completely strange to have a minister for the environment happy to bulldoze bushland with an election only a few months away which could mean that project is stopped," she said.

Roe 9 decision could also affect election

If completed, Roe 8 would reach a yet-to-be constructed interchange on Stock Road.

WA Labor has labelled it a "road to nowhere" because no route has been confirmed for the second stage, known as Roe 9, into Fremantle.

Bill Marmion declined to say if the Government would reveal the Roe 9 route before the election. ( ABC News: Andrew O'Connor )

The original plan to expand Stock Road and a section of Leach Highway caused a public backlash from residents and businesses in suburbs like Palmyra who faced having their properties resumed and demolished.

The Government subsequently floated the idea of a tunnel to the Stirling Bridge in Fremantle, but still had no clear plan to get the link across the Swan River and into the port.

The decision on Roe 9 could prove critical to the March 11 state election, with Liberal MP Matt Taylor facing a tough battle to hold the seat of Bicton.

The Roe 8 extension runs through the Labor-held seat of Willagee, and then continues to Stock Road in the Labor seat of Fremantle.

But three of the roads potentially most affected by Roe 9, Leach Highway, High Street, and Stirling Highway, are either in or on the border of the Bicton electorate.

If the Barnett Government resolved the question of Roe 9 by selecting the route and choosing a tunnel, it could significantly ease the pressure on Mr Taylor's campaign to hold the seat.

Transport Minister Bill Marmion refused to say if Roe 9 was on the agenda for the final Cabinet meeting scheduled for next week.

"I'm not going to divulge ... I don't want to divulge what may or may not be going to Cabinet on Monday," he said.

Mr Marmion was pressed on whether voters in Bicton and other affected electorates would be told about the Government's preferred Roe 9 route before the election.

"When we go into election mode full-time, that'll be part of the decision making of the people involved in that," he said.

The Liberals have indicated they intend to begin officially campaigning from February 1.