Aerospace giant Bombardier could find out this week if it's secured a game-changing order for its C Series from US airline Delta.
Delta Air Lines is looking to order dozens of new narrow-bodied jets - and Canadian firm Bombardier is in the running to secure the multi-billion dollar order.
A fresh contract for the Bombardier C Series would be a boost to the company's operations in east Belfast, where it employs 5,000 people.
The wings of the C Series are built in Belfast in a £520m investment by the firm - the biggest inward investment ever in the province.
The programme to build the C Series - a passenger jet to rival Boeing and Airbus - has been dogged by setbacks and delays, and the jet has not received a firm order since September 2014.
Delta is expected to reveal who it will be placing its order with during a conference call as it discusses its first quarter results for 2016 on Thursday.
According to news agency Reuters, Bombardier executives were in Atlanta, where Delta is based, last week.
Stephen Kelly, chief executive of lobby group Manufacturing NI, said: "We've remained very positive about the success of the CSeries. It's a great, innovative aircraft and great products will always have their time."
"Hopefully this speculation turns into a significant order very soon. That would be a tremendous boost of confidence for the company and of course the local workforce and supply chain."
A spokesman for Delta said: "Delta has been evaluating new and used aircraft acquisition opportunities in the roughly 100-seat gauge as we've continued to replace our 50-seat regional fleet with larger, more customer friendly mainline aircraft."
Asked if the C Series was in the running, he said: "Delta has been public that we are evaluating the CSeries, as we have evaluated all aircraft options available to us."
And a spokeswoman for Bombardier said: "We do not comment on speculation. Bombardier Commercial Aircraft is engaged in a number of sales campaigns around the world, and details of these campaigns are confidential."
Last month, United Airlines announced an order to purchase 25 new Boeing 737-700 aircraft. The order was in addition to the previously announced order of 40 737-700s for $3.2bn - and a blow to Bombardier, which had been tipped to get the deal.
It's believed lower prices for the end of line 737-700s - which are being phased out as Boeing moves to the 737 MAX jet - made Bombardier less competitive.
And Southwest also opted for 33 of Boeing's 737-800 aircraft - after Bombardier had also offered the C Series to Southwest.
One US aviation analyst said: "If Delta Air Lines does go for C Series, I think it would change the landscape significantly."
Both United and Southwest announced their Boeing deals on the same day as conducting their earning calls - leading to speculation that Delta could unveil its order on a conference call about its quarter one results on Thursday.
Bombardier is also waiting to see whether Canada's government will give the C Series programme a cash boost.
The regional government in Quebec, where Bombardier is based, has already ploughed $1bn in the C Series programme in return for a 49.5% equity share.