The forestry peace deal appears dead, with a key MLC now unlikely to vote for the legislation.
Elwick MLC Adriana Taylor was reckoned to be the deciding vote when the Legislative Council held off voting on the Tasmanian Forests Agreement Bill in December.
Mrs Taylor yesterday gave the strongest indication yet that she would not support the Bill in tomorrow's vote.
Mrs Taylor said it may be too difficult to fix the flawed legislation.
''I am doubtful that we can make sufficient and appropriate amendments that will make this a good Bill, and one that is also acceptable to the lower house,'' Mrs Taylor said.
Without Mrs Taylor's support MLCs are expected to be split evenly with President Sue Smith using her casting vote to reject the Tasmanian Forests Agreement Bill.
Mrs Taylor made the comments during a debate noting the select committee's report yesterday.
The final vote will be held tomorrow after MLCs consider a raft of amendments.
Environment and industry groups who spent more than two years negotiating the agreement have consistently said that any changes to the core elements of the agreement, such as the sawlog quota or proposed reserves, would be a deal-breaker.
The government and five legislative councillors backing the deal have also said they would not support any changes that the signatories opposed.
Select committee chairman Paul Harriss said the report showed the depth of problems with the legislation and said it should not be supported.
Murchison MLC Ruth Forrest, who supports the agreement, urged legislative councillors not to send the legislation to committee unless they wanted it to succeed.
''If you are going to vote against it, vote against it now, don't draw it out and make it even harder,'' Ms Forrest said.
The state government is expected to put forward 192 pages of amendments tomorrow, including 150 pages altering the proposed land process than were presented to the select committee in January.
Legislative councillors are also expected to put forward amendments.
Changes to shore up the guaranteed supply of specialty timbers were flagged by Launceston MLC Rosemary Armitage, who said the forestry industry ought not be saved at the expense of the specialist timber and boat building industries.
Nelson MLC Jim Wilkinson said the specialty timber supply could not be met without reserves that had been included in the nomination to extend the South West Wilderness World Heritage Area.
Ms Armitage said the legislation had to be amended, but said there would be no industry without the agreement.
A proposed amendment by Rumney MLC Tony Mulder to increase the sawlog quota from 137,000 to 155,000 cubic metres is not likely to be supported in committee.
Representatives of the signatories watched the debate yesterday but did not return calls.