The Ballymena-based 'Boris Bus' maker Wrightbus will this weekend hold last-ditch talks with a prominent Irish transport executive in a bid to stave off collapse.
Sky News has learnt that Darren Donnelly has emerged as the leading contender to acquire Wrightbus, which employs about 1400 people and counts Transport for London (TfL) among its biggest customers.
Sources said that without a rescue deal being concluded by next week, the company could be forced to appoint administrators.
The news comes just seven weeks after Boris Johnson told the House of Commons that the government would do "everything we can" to salvage Wrightbus's future.
Asked by the DUP MP Ian Paisley whether ministers would step in to save the company, the prime minister said: "It was of great value to the people of this country and I think it's a great company and we will make sure, I give my assurance, we will do everything we can to ensure the future of that great UK company."
It was unclear on Friday evening whether the government had any formal role in discussions about rescuing Wrightbus.
The Routemasters commissioned by Mr Johnson during his tenure as Mayor of London, which became known as 'Boris Buses' because of their distinctive look, are made by Wrightbus.
Talks between Mr Donnelly and Wrightbus's advisers are understood to have accelerated in recent days amid fading hopes of a takeover by Weichai, a subsidiary of the Chinese company Shandong Heavy Industry.
A source close to Weichai said it remained possible that it could acquire Wrightbus but conceded that the possibility had begun to recede.
A number of other bidders are also said to have walked away from the process amid a series of deadlines this week.
Mr Donnelly is a former co-chairman of and shareholder in Retlan Group, a manufacturer of articulated trucks.
Retlan was sold to a Chinese buyer, CIMC Vehicles, in 2016.
The urgency of the talks involving the fate of Wrightbus underline the importance of its role as one of Northern Ireland's most prominent exporters.
If Wrightbus did collapse, it would be a severe blow to the local economy following job losses at Bombardier, the aerospace group, and the crisis at shipbuilder Harland and Wolff.
Sky News revealed in July that Wrightbus had hired Deloitte, the professional services firm, to court potential buyers after a financial downturn that has left it facing heavy losses.
Annualised losses are currently running to approximately £15m, and the company may need a capital injection of at least £30m, insider said in July.
Wrightbus has had a presence in Ballymena for decades.
Sir William Wright, who founded the company with his father in 1946, was knighted in last year's New Year Honours list for services to the bus industry and the UK economy.
In its current form, Wright Group became the world's first developer of a hybrid-electric double-decker bus in 2006.
Wright Group, which also counts Volvo and the Kowloon Motor Bus company in Hong Kong among its big export customers, has already been forced into making redundancies.
In June last year, it said it was axing 95 jobs across its operations in a move which angered union representatives at Unite.
That followed an identical round of cuts three months earlier.
In addition to its bus-making unit, Wright Group encompasses a chassis design arm, EN-Drive.
Neither Wright Group nor Mr Donnelly could be reached for comment, while Deloitte declined to comment.
