The Morrison government is to appoint a new ABC chairman immediately as fallout continues over the sacking of managing director Michelle Guthrie.

More leaks to the media overnight indicated that supporters of Ms Guthrie now were targeting all other ABC board directors following the forced resignation on Thursday of chairman Justin Milne.

Communications Minister Senator Mitch Fifield was expected to expedite an Executive Council appointment of a new chairman by lunchtime on Friday through the signature of the Governor-General, Sir Peter Cosgrove.

Senator Fifield is understood to be considering, among others, three possible current ABC downtable directors: former commercial TV network executive Peter Lewis, company director and Queensland University of Technology business school adjunct professor, Dr Kirstin Ferguson, and board newcomer, Melbourne investment banker and Sydney Institute director Joseph Gersh.

A communications department investigation by secretary Mike Mrdak so far is continuing in an attempt by Minister Fifield to reassure the public that allegations of political interference in the ABC would be fully examined.

Both the minister and former prime minister Malcolm Turnbull have publicly insisted that at no time did they seek the sacking of any ABC staff journalist, while reserving their right to complain about accuracy and impartiality in their work.

Significantly, in an extensive ABC TV interview with 7.30 presenter Leigh Sales, ousted chairman Mr Milne also exonerated the government, while asserting he had never ordered Michelle Guthrie to sack economics correspondent Emma Alberici or political editor Andrew Probyn.

Mr Milne said he could not recollect telling Ms Guthrie to “shoot” Mr Probyn. He had not written any email in which he had instructed that Ms Alberici’s employment be terminated. Mr Milne, however, conceded his interactions at board and management level were centred around the sensitive relationship with government that funded the ABC.

“You can’t go around irritating the person who’s going to give you funding again and again and again if it’s over matters of accuracy and impartiality,” he said.

Mr Milne revealed he had been pushing for around $500 million in capital funding from government for rebuilding the ABC’s digital infrastructure with technology known as Jetstream.

In another leak to The Sydney Morning Herald the full text of an email responding to one sent to Mr Milne by Ms Guthrie about Ms Alberici was published on Thursday:

“After two glasses of red of course there’s an agenda. They fricken hate her. She keeps sticking it to them with a clear bias against them. We clear her as ok. We r tarred with her brush. I just think it’s simple. Get rid of her. My view is we need to save the corporation not Emma. There is no g’tee they will lose the next election [sic].”

Some commentators are now demanding that the entire ABC board be removed following accusations that directors did nothing about Ms Guthrie’s allegations of political interference by Mr Milne over the work and employment of Ms Alberici and Mr Probyn.

If it continues the Mrdak inquiry, or a Senate committee of inquiry soon expected to be established, would be expected to interview all ABC directors to seek all relevant documentation and explanations on the motivations behind their decision to sack Ms Guthrie.

The Guthrie allegations are believed to be contained in lengthy documents sent in confidence and without prejudice to the ABC board by Ms Guthrie during weeks of negotiation about what was intended initially to be her mutually agreed departure.

Directors will be asked if alarms bells about the Milne allegations rang with them and if, in wanting to remove Ms Guthrie, they were complicit in any political interference.

On Friday last week Ms Guthrie is understood to have refused to resign by mutual agreement with a negotiated severance payment, leaving the board on Monday to execute a contract power to terminate her employment “without cause and with immediate effect”.

The damaging leaks to the Herald and Sydney’s Daily Telegraph followed on Tuesday, Wednesday and Thursday and has embroiled the ABC and the government in unprecedented contumely.

In other fallout from the sacking of the MD and the resignation of the chairman there is now a national debate about partisan stacking of the ABC board and the government’s damoclesian leverage over the ABC through Cabinet-approved triennial funding.

For the first time the Bill Shorten Labor Party has announced the future and survival of the ABC as a mainstream bulwark of Australian media and content creation will be a major federal election issue.

But so far the ALP has only committed to rescinding Senator Fifield’s $83.7 million ABC funding cut to be applied from July 1 next year. Labor has been silent on the $254 million defunding of the ABC since the 2014 budget delivered by then treasurer Joe Hockey, dishonouring a 2013 pre-election commitment by then incoming prime minister Tony Abbott: “There will be no cuts to the ABC or SBS”.