The government had planned to have ACTTAB sold by June, but the date was pushed back in the budget, with an announcement now imminent.

The frontrunners to buy the betting agency are believed to be the two big TAB owners - Tabcorp, which owns the former government TABs in NSW and Victoria; and Tatts, which owns the TABs in Queensland, the Northern Territory, South Australia and Tasmania. A third bookmaker was also shortlisted for the purchase, but the government appears keen to sell to a TAB owner.

Staff are worried about their futures and union organiser Rudi Oppitz, who will travel from Wollongong for Wednesday's meeting, said they had been left in the dark too long.

"The communication level that has taken place is really disappointing, particularly for the staff that have been in this limbo for such a long time. There's a great level of uncertainty and hopefully we'll get some clarity during the day tomorrow [Wednesday], but I'm not necessarily holding out much hope for that," he said. "At the end of the day, the ACT government's handled this quite poorly."

It is unclear how many staff will get jobs with the new agency, with Mr Oppitz saying they had not even been told whether the new company would want shopfronts in Canberra. Staff were also concerned about access to redundancy payments.

Treasurer Andrew Barr has said that jobs would be considered as part of the sale, with bidders asked about plans for employment.

The government is also taking account of support for the racing industry. It subsidises local racing by $8 million a year and Mr Barr has said he would consider what companies were prepared to do for the racing industry as part of the sale.

It is selling ACTTAB after some years of falling turnover and profits, as punters shift to bigger players and smartphone betting.