A meeting which could determine the fate of planned new North-East train services will be held today.
The Office of Rail Regulation (ORR) will host a hearing at the request of GNER, at which rival railway company Grand Central is expected to be present.
Both companies are awaiting the final outcome of applications to the regulator for new services, which will be known later this month.
GNER, which has seen its bid for a further 12 services between Leeds and London provisionally rejected, is expected to argue that its ten-year East Coast Main Line franchise contract with the Government includes a requirement for the extra trains.
It will also point out the economic benefits of such a plan.
For its part, Grand Central hopes the regulator will at least rubber stamp a "minded to" decision to approve three, or possibly four, new daily services from Sunderland to London Kings Cross, via Hartlepool, Eaglescliffe, Northallerton and Thirsk .
The ORR is known to have concerns about congestion on the East Coast Main Line, which both firms will have to share, and who will take up any spare slots.
Martin Murphy, North-East chairman of rail lobby group Rail Future, said: "Grand Central has an excellent package which gives a hugely improved deal for people travelling into, as well as out of, the Durham coastal area.
"There are umpteen trains already going to Leeds every day and we believe it is about time other places got a look in."
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