About 1,000 jobs could be created in County Durham if Japanese firm Hitachi decides to build carriages for "super express" trains in the area.
The industrial giant was provisionally awarded the £7.5bn government contract last year and must now choose a suitable location for the plant.
The firm said Newton Aycliffe was the "first choice". Another site in North Wales has also been short-listed.
If government approval is granted, trains could be in operation in 2015.
A spokesperson for Hitachi said up to 200 people would be involved in the construction of the new plant.
A further 800 would be employed in manufacturing the trains - which could begin in 2013.
The trains are designed to be faster, greener and able to carry 21% more passengers.
Phil Wilson, MP for Sedgefield, said: "If we get this it would be the biggest investment in the north-east of England since the Nissan car plant in Washington.
"The North East is the place to have it. Everyone agrees we need to re-balance the economy.
"Public sector employment here is significant but that's not an argument for cutting public sector jobs, it's about growing the private sector as well."
The government is expected to make an announcement in October on whether to approve the Hitachi consortium plans and site location.
The consortium, called Agility Trains, also includes John Laing and Barclays Bank.