Market sources said Amec and Costain are in alliance talks and that a group including Simons, Osborne and Bowmer & Kirkland are soon to close a partnering agreement for the roll-out programme.
Sources also said talks were under way between Gleeson, Balfour Beatty and Skanska for another grouping. The consortiums could eventually include large consultancy groups such as Atkins and Capita.
The joint-venture deals are expected to be finalised by early next month. The work is expected to be worth £300m a year to successful consortium members, and will require about 600 staff. One of the reasons for firms' grouping together is to meet the wide geographic demands of the programme, which stretches from Cornwall to Northumberland.
Some major contractors, such as Kier, Carillion and Laing O'Rourke, are expected to bid on their own.
One source said some contractors would bid both on their own and as part of teams. The source said: "A lot of people are hedging their bets right now. Because there are a limited number of places, one needs to be realistic about one's prospects."
The national structure of the programme has already attracted criticism from regional contractors.
One said: "The NHS have made an absolute pig's ear of it; they have not listened to the industry.
By making it a national programme rather than a regional one they are turning decent regional contractors into subcontractors.
A joint venture will not have any culture to it."
Client NHS Estates launched the national roll-out last December and is due to select 12 "principal supply chain partners" for the four-year programme this autumn.