Chief Minister Katy Gallagher will resign the chief ministership on Wednesday, but it is still not clear precisely when she will vacate her seat. Ms Gallagher has said she will leave the Assembly before Christmas, but has not given a date.
The ACT Electoral Commission cannot begin the countback of votes for her seat until it is officially advised by Speaker Vicki Dunne that Ms Gallagher has resigned.
Labor's caucus meets on Wednesday to endorse Andrew Barr and Simon Corbell as leader and deputy leader. The Assembly will hold a special sitting, probably on Thursday morning, where, from her position on the backbench, Ms Gallagher will help elect Mr Barr as the new chief minister, in a secret ballot.
She will not leave the Assembly before then, otherwise she would leave it tied on an 8-8 vote for chief minister. But presumably sometime soon after the vote, she will give a date for leaving the Assembly, at which point Electoral Commissioner Phillip Green can begin the countback for a replacement Assembly member.
Mr Green doesn't expect to begin that countback until after the Christmas-New Year break, to avoid crossing over the holiday period. He will notify the vacancy in a newspaper advertisement, inviting candidates who stood in Ms Gallagher's seat of Molonglo at the 2012 election to contest the vacancy. They have 10 days to notify their interest, then their names will be entered into the computer for the countback.
Mr Green said the successful candidate would be known the same afternoon, but before official declaration of the poll, he would give people a couple of days to request a recount, and give the successful candidate a chance to resign from any public service position he or she might hold.
Ms Gallagher won 23,996 first-preference votes. All of them will be distributed in the recount, with Meegan Fitzharris, chief of staff to Andrew Barr, expected by Labor number-crunchers to win comfortably.
Mr Green said the earliest he expected to be able to start the recount was January 5, which would mean a count on January 15 and another few days before the declaration of the poll. The term of the new Assembly member begins on the night of the declaration of the poll.
Ms Gallagher is expected to take up her Senate seat in April after Kate Lundy leaves. But first she must go through a Labor pre-selection.
The ACT Labor Party opened nominations on Monday for the spot, and eligible party members have until December 18 to put up their hands. They must have belonged to the party for two years and have five party members supporting their nomination.
If Ms Gallagher's is the only nomination, she will be declared the winner on December 18. If anyone else decides to nominate to force a ballot, it will be held on January 28, 29 and 31, with members having three opportunities to vote before a count on January 31. The winner will be declared on February 2.