Two-thirds of the public servants faced with moving to Armidale under Barnaby Joyce's "farcical" plan for de-centralisation would refuse, the workers' union said.
Professionals Australia ACT director David Smith also said attempts by the Nationals to keep their coalition deal with the Liberals secret added to fears of further relocations of Canberra public servants to the regions.
Mr Smith said any value in moving the Australian Pesticides and Veterinary Medicines Authority 750 kilometres north was questionable, given a $24.1 million commitment for relocation costs and potential redundancy liabilities of up to $10 million.
"As a first test of economic credibility, to still be going ahead with a cost-benefit analysis despite the fact they've already made the decision and allocated money to move is just farcical," he said.
The move had been speculated for more than a year before Deputy Prime Minister Barnaby Joyce, the agriculture minister, made the announcement during the election campaign on June 9. Mr Smith said he expected little had changed since a staff survey in mid-2015 found about 110 people would not uproot their lives to go to Armidale in Mr Joyce's northern NSW electorate.
A spokesman for Mr Joyce said this week the cost benefit analysis report on the relocation was still to be finalised and provided to the agriculture department, but the government would consider any transition arrangements it raised.
"It is also worth noting that whilst economic modelling is an important consideration, decentralisation of the APVMA is also about creating centres of excellence in regional areas with government agencies partnering with regional universities and industry research organisations to become agricultural research hubs," he said.
The spokesman said no decision on the future location of the Murray Darling Basin Authority "over the longer term" had been made, and no cost benefit analysis for any move from Canberra had been commissioned.
Mr Smith said with the details of the renewed coalition agreement unknown he had no confidence the basin authority, which employs about 300 staff, would remain in the national capital.
National Farmers' Federation president Brent Finlay called for the release of the cost benefit report by EY into the pesticides authority last month, saying he wanted an assurance the move would not hurt farm businesses.
"The NFF has always been concerned moving the APVMA would result in a loss of highly specific and skilled regulatory scientists and damage organisational continuity, which would delay the already difficult registration process for new pesticides and medicines," Mr Finlay said.