ACT Treasurer Andrew Barr says new modelling shows a dire economic outlook for the Territory should the Coalition win Saturday's federal election.
Mr Barr asked Treasury officials to prepare the modelling based on Coalition plans to cut 12,000 public service jobs through natural attrition.
It is not known how many of those jobs would go in the ACT.
But Mr Barr says even if it is about half, employment growth in the ACT would be set back more than three years.
"The economic impacts of that within the Territory would be in the order of a $650 million loss in gross state product," he said.
"That would impact particularly hard in Tuggeranong and Belconnen where we would anticipate more than half of that impact would occur in those two areas. It would also spill over into south-east New South Wales."
Liberal ACT Senate candidate Zed Seselja has dismissed Mr Barr's claims.
"He's got his numbers completely wrong. He's assuming that it will all happen in Canberra and of course he's ignoring now the 12,000 - 14,000 job cuts that are coming under Labor.
"Andrew Barr is trying to cover for the fact that I think that it is his massive tax increases here in the ACT which is contributing to low business confidence, which has contributed to a slowing economy."
Mr Barr did not ask for modelling under a continued Labor Government, but he denies he is playing politics on election eve.
"The implications of what the Commonwealth Government does has significant flow on effects to the Territory economy," he said.
"We will need to make adjustments to our land release program, we particularly anticipate impacts on population growth. So we need this data in order to make future budget decisions."