And McGrath believes finding a new chief executive should be the "highest priority" and it's taken too long for the board to begin their search for a replacement of Michael Jones, who parted ways with the Brumbies at the end of April.

The Brumbies declined to comment on McGrath's blog, although they did confirm director Peter Callaughan had stepped down for "personal reasons".

McGrath sent shockwaves through the Canberra rugby community when he posted a blog on the Griffin Legal website on Thursday as the Brumbies continue to lurch from one controversy to the next.

He spent six years as the Brumbies chairman and then five in the same post with the ARU.

McGrath listed 19 points as to why Kennedy needed to step down because he was "concerned" the Brumbies' brand was being damaged.

He said the two-time Super Rugby champions had "one of the strongest brands in the world", but not any more.

McGrath said he couldn't wait until the Brumbies annual general meeting in November because something needed to be done now.

He continued his call for Kennedy to step down and said the Brumbies chairman's position was "untenable".

The Brumbies are facing a nervous wait to see whether major sponsor Aquis will pull out, which depends on the result of the upcoming ACT election and could leave the cash-strapped Brumbies in financial strife.

"I felt sick yesterday having to put this out but someone has to say something. We can't just sit there and do nothing when there are serious issues," McGrath said on Friday.

"Someone has to step up, there's nothing in this for me ... our reputation is diminishing all the time.

"We have one of the strongest brands in the world, it is suffering. I'm worried about the brand, I'm worried about where we're going.

"If we wait until November we could've lost control. What if the government lose the election? What if Aquis walk away?"

The Brumbies initially tried to stand Jones down in March, but he launched legal action before he eventually accepted a payout more than a month later.

ARU integrity manager Phil Thomson was installed as the acting boss on May 12 and has been in the role for almost three months.

The Brumbies board is yet to advertise for a new CEO but said they were going to do so in the next couple of weeks – for the past couple of weeks.

McGrath said Thomson was a "good man" but emphasised how important the position was and a new one was needed as soon as possible to begin work on the 2017 season.

He said if an appointment wasn't made soon then next season, which begins in February, would be "done".

"Absolutely, it's taken too long. There's no doubt in my mind it's taken too long," McGrath said.

"[Thomson] ... he's a good man, there's no doubt about that, but that's no substitute for making a proper appointment and going through the process.

"When you're looking for a CEO, it is the highest priority, it is not the lowest priority."

In a statement, Kennedy confirmed Callaughan was no longer a member of the Brumbies board.

He said it was a mutual decision that was made in the best interests of the Brumbies due to personal reasons.

Callaughan joined the board in 2014 when Kennedy was elected chairman, taking over from Sean Hammond.

"Peter has continually provided great contributions to our organisation in his role as a director over the past 19 months," Kennedy said.

"At a previous board meeting, he indicated that due to personal reasons, he was not able to successfully continue to fulfil the role of director with ACT and Southern NSW Rugby."