The Rudd Government is set to emulate the Howard government and override or disallow ACT legislation, unless talks in the next 48 hours reach a compromise.

The Federal Government yesterday unveiled plans to fulfil election commitments to amend about 100 laws to ensure superannuation, taxation and social-security rights for same-sex partners.

However, it remained intransigent on ACT plans to institute ceremonies formally recognising same-sex unions, declaring they "mimicked marriage". It also maintained opposition to gay and lesbian couples having access to IVF and adoption.

ACT Attorney-General Simon Corbell announced yesterday a substantial compromise, offering to remove a state-sanctioned official from the ceremonies, to be replaced by authorised witnesses.

This is expected to be a critical bargaining chip in his discussions today or tomorrow with his federal counterpart, Robert McClelland.

It is understood that the Federal Government has not wanted any mention of any ceremony in the legislation, mirroring the previous government's position, and virtually gutting the legislation.

Former Attorney-General Philip Ruddock and former Territories Minister Jim Lloyd advised the Governor-General to disallow the ACT Civil Unions Bill, provoking the ACT's Gary Humphries to become the only Liberal senator to cross the floor and vote against the Howard government.

Mr Corbell made clear yesterday that he intended to re-introduce the legislation - with or without federal agreement - before October's ACT election.

He acknowledged that his Labor colleagues could override him in exactly the same manner as the Howard government.

"I hope it does not come to that, but certainly the Commonwealth have not ruled that out," he said.

"And that remains a matter of very significant concern for the ACT.

"We reject completely any suggestion that there are any grounds for intervention in the ACT's affairs.

"We are self-governing and we are entitled to make these laws."

The ACT Self-Government Act was anachronistic and undemocratic, grounded in 19th century thinking, Mr Corbell said.

Describing negotiations as being at "a very critical point", he said, "In one to two days, we will be in a position to make a final announcement on how this legislation will progress."

Mr McClelland continued to speak of the ACT legislation providing for ceremonies replicating marriage and restated his belief that a uniform system of same-sex relationship registers was the best route.