One consortium, led by Lockheed Martin, claims that 2,000 high-technology jobs and Britain's leadership in airborne radar surveillance is at stake, along with pounds 3bn worth of export business if it loses the order.
But the other consortium, led by its US rival Raytheon, claims that its bid will bring just as many, if not more, benefits to Britain and says it has signed up 85 UK companies as industrial partners.
The two consortia, and a third one led by Northrop Grumman, are bidding to meet the Ministry of Defence's requirement for an Airborne Stand Off Radar (Astor).
The radar system will be fitted into high-speed business jets and used to beam surveillance data back to military commanders at ground stations.
The Lockheed consortium, known as TeamAstor, says that it is offering a purpose-designed British radar built by Racal. Other companies involved in the consortium include Logica, Marconi Electronics Systems and Marshall Aerospace.
Keith Robinson, managing director of the Portsmouth-based Lockheed Martin's UK government systems division, said: "TeamAstor is a British team for a British requirement, ensuring the highest gains for Britain economically, technologically and operationally."
He said Britain would gain 2,000 direct high-technology jobs and a further 2,000 from exports and 100 per cent UK industrial participation.
All work on the radar would be carried out in the UK, enabling British radar technology to leapfrog the competition and ensuring the benefits of a pounds 3bn export market flowed directly back to British companies.
But the Raytheon consortium said it would also provide at least 2,000 jobs through its British partners while the aircraft it would fit the radar onto, the Bombardier Global Express, had a higher UK content than the Gulstream 5, which TeamAstor was offering.
A spokeswoman also pointed out that part of the Racal radar was being developed by Raytheon itself. "TeamAstor trying to wrap themselves in the flag is a bit rich," she added.
The rival bids are due to be assessed by the MoD's equipment approvals committee at the end of this month and a decision is expected by March.
The contract has a fixed price but the Raytheon consortium says it is offering a better deal. Raytheon says it will supply five aircraft and 11 ground stations whereas TeamAstor is offering four aircraft and nine base stations.
But TeamAstor says the first two Raytheon systems will be developed in the US, reducing the level of British involvement.