ACT Chief Minister Andrew Barr revealed his cabinet would expand by one on Monday, citing a growing workload with the city's population soon to hit half a million people.

The new minister will be announced on Thursday, while their portfolios will be announced on Friday.

Tara Cheyne ruled herself out of the contest early, saying she wanted to focus on being a local member.

"This is not to say that I won't seek opportunities at a future date," Ms Cheyne wrote in a statement on Facebook.

"However, my primary responsibility as the Member for Ginninderra is serving - and actively considering how I can best serve - my constituents.  I was elected on the basis of being an accessible local member and this remains my focus."

Ms Cheyne also said her campaigning to restore territory rights would have to take a back seat if she was promoted to the ministry.

That leaves Chris Steel, Bec Cody, Suzanne Orr and Michael Pettersson in contention for the ministry.

Sources within Labor said it was shaping up to be a contest between Mr Steel and Ms Cody, who both represent the south Canberra electorate of Murrumbidgee.

Mr Steel is from Labor's right faction while Ms Cody is from the left.

There are three left faction ministers in Mr Barr's cabinet - Yvette Berry, Rachel Stephen-Smith and Mick Gentleman

Andrew Barr and Meegan Fitzharris are from the right faction while Gordon Ramsay is unaligned. The seventh minister, Shane Rattenbury, is a Green.

Ms Orr is also from the left faction, while Mr Pettersson is currently unaligned after splitting off from the right in the last fortnight.

News of the reshuffle came nearly a week after the ACT Opposition asked Mr Barr to reduce the workload of health, transport and higher education minister Ms Fitzharris "so that she can get at least something done right".

At the time, Mr Barr said the issue of workload had already been raised by one of his colleagues.

Asked on Tuesday whether she would still be health minister at the next election, Ms Fitzharris said that would be up to Mr Barr.

"It’s an incredible portfolio, it’s an enormous privilege to hold the portfolios I have, all ministers work very hard and we look forward to a new minister joining us," Ms Fitzharris said.

Pushed further, she said she would "personally love to continue as the minister for health" although "whoever is appointed as a new minister will do a great job".

Mr Rattenbury said the prospect of a new minister had "been in the offing" for a while.

"When the Assembly expanded to 25 the allowance was made to have up to nine cabinet ministers and there’s no doubt that each of the ministers carries a large number of portfolios, I think it will benefit the Canberra community to split the workload and give ministers more time to focus on what they need to deal with," Mr Rattenbury said.

Liberals' health spokeswoman Vicki Dunne said she hoped Ms Fitzharris ended up with a "lighter workload".

Opposition gambling spokesman Mark Parton said he wanted Gordon Ramsay to lose the gaming and racing portfolio as "he is not the minister for gaming and racing , he is the minister against all gaming and racing".

Liberals leader Alistair Coe questioned if the cabinet expansion was a way for Mr Barr to hold onto power in his party, given the factional wrangling occurring between Labor's left and right.

Mr Barr said it was ironic the Liberals chose to question his leadership on the same day their party was "imploding".

"Nearly 40 per cent of the party room three kilometres from here have just voted to get rid of another prime minister," Mr Barr said.