The owner of the Grangemouth plant is expected to announce today whether it will reverse a shock decision to close the site, safeguarding hundreds of jobs.
Ineos has been discussing a change in position by the Unite union whose members now say they will commit to a plan aimed at securing its future.
The petrochemicals plant and adjoining oil refinery making up Scotland's largest industrial complex was shut down last week in advance of a planned walkout over pay and conditions.
Ineos did not restart the site after Unite called off the strike but wrote to staff asking them to sign up to changes such as a pay freeze and the closure of the final salary pension.
The company insisted on Wednesday it had no alternative but to close the plant after it failed to persuade its staff to accept the survival plan but Unite general secretary Len McCluskey said yesterday the union would embrace it "warts and all".
A statement is expected from Ineos today on the petrochemical business which employs 800 people directly and a further 2,000 sub-contractors.
"We are not going to let this plant close," Mr McCluskey said last night.
"This plant is on cold shutdown and each day that goes by makes it harder to start back up again, which is why the stewards made the offer to the company - so that we can get people back to work."
UK government officials have admitted it would be a "challenge" to find another company to buy the business, which Ineos has said is losing £10 million a month.
The losses, scale of investment needed to upgrade the site, coupled with the industrial relations would all have to be considered by any potential buyer, officials said.
But they insisted there would be no shortage of fuel supplies as a result of the dispute.
Ministers from the Scottish and UK government held talks with Unite and management yesterday and said that both administrations were doing all they could to keep the site open.
Scottish Secretary Alistair Carmichael said: "It's clear that we're dealing with a different situation following the statement from Unite that they were prepared to accept the Ineos survival plan without any pre-conditions.
"There remains of course a great deal to be done."
Mr Carmichael said the decision about the future of the plant lies ultimately with company shareholders.
Unite and Ineos have been embroiled in a bitter dispute for weeks, initially over the treatment of Unite convenor Stephen Deans, who was involved in the row over the selection of a Labour candidate in Falkirk, where he is chairman of the constituency party.
He was suspended, then reinstated, and is facing an internal investigation, which is due to report today.
The dispute dramatically widened to the future of the entire site, with Ineos warning that it would close without fresh investment and changes to pay, pensions and other conditions.