A cloud of scandal has settled over Canberra ahead of an “explosive” report into alleged misconduct of federal ministers, with the ABC accusing the government of applying “extreme and unrelenting” political pressure.

“Senior politicians” are in the firing line, with former Prime Minister Malcolm Turnbull claiming some MPs may be exposed to “compromise”, but current PM Scott Morrison has warned the ABC to stay within its charter.

Mr Morrison also said the ABC should turn the spotlight on all MPs “across the political spectrum”. It has set up a potentially explosive showdown in a Senate hearing late on Monday, just minutes before a news report – currently the talk of the town – is due to air.

The ABC’s Four Corners program has been advertising its episode Inside The Canberra Bubble since late last week, promising an “explosive expose” of allegations against politicians.

“It is vitally important that all politicians maintain the highest possible standard of proper conduct.” An explosive expose from @Milliganreports, Monday on #4Corners Here’s a preview pic.twitter.com/9x4K89iFoL

— Sally Neighbour (@neighbour_s) November 4, 2020

A teaser video says the report, to air Monday night, “questions the conduct of some of the most senior politicians in the nation”. The New Daily understands the subjects of the episode include potentially two senior ministers in the Coalition government.

Mr Turnbull, Greens senator Sarah Hanson-Young and Liberal senator Concetta Fierravanti-Wells appear in the program.

Former Labor MP Emma Husar, who quit politics in 2019, tweeted “finally” in response to the report.

The program has been the subject of weeks of gossip in political circles.

Ahead of its release, Four Corners executive producer Sally Neighbour claimed “political pressure” that was “extreme and unrelenting” had been applied to the ABC’s leadership over the report.

The political pressure applied to the ABC behind the scenes over this story has been extreme and unrelenting. All credit to the ABC’s leadership for withstanding it. ‘Inside the Canberra Bubble’, tonight on #4Corners pic.twitter.com/z0o9PijASu

— Sally Neighbour (@neighbour_s) November 8, 2020

Ms Neighbour did not elaborate on her claims, but The Australian reported that government members had contacted senior executives at the ABC.

The Australian reports Mr Turnbull will make allegations about a 2017 function at a Canberra bar, which is a favourite of political staffers and journalists.

Mr Turnbull famously instituted a ‘bonk ban’, outlawing relationships between politicians and their staff, after the 2018 scandal surrounding former deputy PM Barnaby Joyce.

On Monday, Mr Morrison didn’t deny his government had contacted the ABC in the lead-up to the Four Corners report. In response to questions, he said” “I don’t even know what’s in it. So I think that it’s a bit difficult for me to respond.

“We would just expect that the ABC always would act in an independent and an unbiased apartisan way,” the PM said.

Former PM Malcolm Turnbull will feature in the report. Photo: Getty

“If they’re going to make inquiries, I would think they’d want to do them across the political spectrum and it’s really for the ABC under their charter to remain true to that.”

Mr Morrison said he supported Mr Turnbull’s ‘bonk ban’ and had continued the rule under his government.

“I was one of its strongest supporters … it’s important as a cultural change within the Parliament,” the PM said.

“All I’m simply saying is the government wants the ABC to stand up for its charter and act consistent with its charter and Australians will make the judgment about whether they do, or they don’t.”

In a sensational twist of timing, ABC senior staff will appear before a Senate estimates hearing late on Monday, while Mr Turnbull will also appear as a guest on the Q&A program right after Four Corners ends.

This Senate schedule was locked in before the Four Corners report was scheduled to run and is not linked to the program’s airing. But questions about the report are likely.

The ABC is due to face Senate questioning on Monday evening, just hours before the report is to air.