Scott Morrison expected to call federal election on Thursday morning

The prime minister, Scott Morrison, is poised to call an Australian federal election on Thursday morning after ministers unveiled a spate of last-minute political appointments to government bodies.

On Wednesday evening the shadow treasurer, Chris Bowen, told Radio National that Labor reserved the right to cancel appointments made in proximity to the caretaker period, in a warning shot to the Coalition not to take advantage of what may be its last days in office if Labor’s small but consistent poll lead holds.

Appointments confirmed on Wednesday included the former Liberal partypresident and Howard government minister Richard Alston, who was added to the National Gallery of Australia council and former Liberal MP Ewen Jones, who was appointed to the National Film and Sound Archive board.

The attorney general, Christian Porter, countered it was “not unusual” to make nominations in a “compressed timetable” before the caretaker period.

Asked on Wednesday night if the election would be called imminently, Porter replied: “There’s an election due before not too long, the prime minister will call that at a time he thinks is appropriate – everyone is gearing up for an election, that much is obvious.”

Key staff are in place in the Liberal party headquarters in Brisbane, and the Labor campaign set up operations in Sydney at the weekend.

Bill Shorten, who has been on a campaign footing since his budget reply last Thursday, flew back to Melbourne on Wednesday night to position for the opening day of the contest. The prime minister was also in Melbourne on Wednesday, but flew in to Canberra in the evening.

The expectation is Morrison will visit the governor-general on Thursday morning before calling an election for 18 May. The prime minister released a video late on Wednesday through his social media accounts framing the coming election contest as a decision about Australia’s direction over the next decade.

Morrison held back from calling the election last weekend to sell the budget. As the major parties roll into the contest, Labor is ahead of the Coalition in the major opinion polls – a position it has maintained for all of the current term.

Labor has spent the unexpected extra week of Senate estimates probing various government departments about the level of taxpayer-funded advertising, which has intensified ahead of the campaign.

On Wednesday, health department officials gave details of a new $5.6m 16-day ad campaign promoting the pharmaceutical benefits scheme, scheduled to finish on Saturday.

Labor’s health spokeswoman, Catherine King, said the government was “spending $350,000 of taxpayers’ cash every single day on blatantly political election-eve ads about a health reform Labor introduced more than 70 years ago”.

The failure of the last Labor government to list new medicines on the PBS has been a central attack by the Morrison government, which Shorten sought to neutralise in his budget reply by committing to list all new drugs recommended by the expert panel.

Although finance department officials were unable to give fresh figures about the total remaining budget for ad campaigns, AusTender documents show that since the start of 2019 the total government ad spend is $136m.

Shorten said the figure proves the Coalition is “spending about $1 million a day of your money telling [Australians] what a great job they’re doing”.

Morrison has campaigned in Launceston, the Gold Coast and western Sydney in the last week, while Shorten has visited Launceston, Melbourne, northern NSW, Brisbane and northern Queensland promoting Labor’s $2.3bn plan to fight cancer contained in his budget reply.

Appointments made by the government in the last fortnight include:

Labor has accused the Coalition of using government appointments – particularly to the Administrative Appeals Tribunal (AAT) – to show favour to former members.

In February Porter appointed six former parliamentarians and eight former staffers from Coalition ranks to the AAT.

Attorney general’s department officials told Senate estimates on Thursday that after that most recent round of appointments a new merit-based process had been introduced.