Lenders to troubled Black Country infrastructure giant Carillion have rejected a rescue plan for the debt-laden group, it has emerged.
A business plan tabled by the group on Wednesday was knocked back because it failed to present a solid proposition for restructuring the business.
Sources have also told the Press Association that the proposal's methodology was found wanting but talks are ongoing.
It comes as the Government, pension authorities and stakeholders are meeting today in an attempt to thrash out a rescue package for the firm that would help it avoid collapse.
Carillion led the development of the Library of Birmingham, which opened in 2013, and is also working on the £700 million city centre Paradise project and last year won tunnelling contracts for high-speed rail line HS2.
But the listed, Wolverhampton-based group is struggling under £900 million of debt and a £590 million pension deficit so will use the meeting to discuss plans for securing its long-term future.
It has also been without a permanent chief executive since July when Richard Howson stepped down in the wake of the firm issuing a profit warning.
And last week an investigation was launched by the Financial Conduct Authority into the timeliness and content of announcements made by Carillion during a seven-month period.
Unions have urged the Government to step in to protect 19,500 jobs that are now at risk.
Shadow business secretary Rebecca Long-Bailey said: "The collapse of Carillion could provoke a serious crisis.
"It would have major implications for the outsourced government contracts the company holds as well as the firm's thousands of workers, those in the supply chain and those who rely on Carillion's pension fund.
"The Government, which, despite warnings, carried on with its programme of outsourcing public services to this company, must stand ready to bring these contracts back into public control, stabilise the situation and safeguard our public services."
Talks between the group and lenders HSBC, Barclays, Santander and Royal Bank of Scotland have centred on options to reduce debts, recapitalise or restructure the group's balance sheet.
A Government spokeswoman said: "Carillion is a major supplier to the Government, with a number of long-term contracts.
"We are committed to maintaining a healthy supplier market and work closely with our key suppliers.
"The company has kept us informed of the steps it is taking to restructure the business."
The Pensions Regulator would not comment on whether it was attending specific meetings, but a spokesman said: "We have been and remain closely involved in discussions with Carillion and the trustees of the pension schemes as this situation has unfolded.
"We will not comment further unless it becomes appropriate to do so."
Rehana Azam, national officer of the GMB union, said: "First and foremost, workers' jobs must be protected.
"It's not right that GMB members working for Carillion should face uncertainty and insecurity through no fault of their own.
"Handing Carillion bosses a blank cheque bailout is completely unacceptable - company bosses should not be rewarded for failure with public money."
A statement from Carillion said: "The company met with representatives of its creditor groups to present its business plan on January 10, 2018.
"Further to this presentation, Carillion continues to engage in constructive discussions with a range of financial and other stakeholders regarding options to reduce debt and strengthen the group's balance sheet.
"Suggestions that Carillion's business plan has been rejected by stakeholders are incorrect.
"It is too early to predict the outcome of these discussions but Carillion expects that any such agreement is likely to involve the raising of new capital and the conversion of existing financial indebtedness to equity which would result in significant dilution to existing shareholders.
"As part of its engagement with stakeholders, Carillion is in constructive dialogue in relation to additional short term financing while the longer term discussions are continuing."