A federal election on May 25 remains a live option, despite speculation Prime Minister Scott Morrison will trigger a May 18 poll this weekend.

The date speculation comes as Mr Morrison and Labor leader Bill Shorten traverse the country spruiking their alternative economic plans on a faux election campaign.

The prime minister has the advantage of rolling out taxpayer-funded election advertising which Labor says is costing $1 million a day.

However, the Liberal-National coalition trails Labor in published opinion polls.

A Senate estimates committee heard on Monday the prime minister’s chief of staff had requested a meeting with the Australian Electoral Commissioner last week to talk about the “mechanics of election timing”.

The AEC on Monday removed a long-standing reference on its website to May 18 being the “last possible date” for a half-Senate and House of Representatives election.

Liberal MP Trent Zimmerman told the ABC: “We are governing right up until the last possible moment.”

Mr Morrison, who has claimed underdog status in the race, has maintained he always had three dates in mind – May 11, 18 and 25.

Going with the May 25 timing would avoid having to pause the campaign over the Easter long weekend.

But the House of Representatives is scheduled to return on April 15 for four days of sittings.

The AEC has maintained a May 25 date is risky because of the tight deadline to count ballots, but it would work to whatever election schedule the government determined.

A later date will also give Environment Minister Melissa Price more time to consider the final scientific advice on the controversial Adani coal mine in central Queensland.

She faces pressure from the Nationals to give the project the green light before the election is called, but some Liberal MPs warn of a voter backlash in city seats if it is approved.

Mr Shorten is expected in central Queensland on Tuesday to unveil a $500 million investment to slash waiting times for cancer treatment and surgery in public hospitals.