Work to widen 44km of motorway between the M23 and M26 and the A1(M) and M11 is expected to be dumped in favour of hard shoulder running.
Widening of large sections of the M1 and M62 motorways is also being considered for hard shoulder running.
The work was to be carried out for the Highways Agency as part of a £5bn DBFO contract which would have resulted in the widening of 101km of motorway and the maintenance of the whole M25 for 30 years.
But the Highways Agency confirmed this week that the DBFO contract will now only cover widening of 57km of motorway from junctions 16 to 23 and junctions 27 to 30. These are the first two of the four sections of motorway to be widened.
"These sections are to be delivered first," said a Highways Agency spokesman.
"We have previously looked at whether hard shoulder running [for these sections] would offer a better solution than the proposed widening but the cost saving from adopting hard shoulder running here would be very small, and possibly zero, when account is taken of all the wider direct and indirect costs of cancelling the DBFO contract.
If hard shoulder running was adopted, costs would fall.
"The £5bn estimate included widening all four sections, plus maintaining the whole motorway for 30 years. If we switched to hard shoulder running for the later sections we would obviously expect the overall price to come down," the spokesman said.
The Agency has delayed the announcement of its preferred bidder for the deal, until at least 2 May, because of the embargo on government announcements ahead of the local and London mayoral elections on 1 May.
Intense negotiations with the Treasury are also understood to have held up the decision.
"The Highways Agency is very close to making a decision on a provisional preferred bidder for the M25 DBFO Contract," said an Agency spokesman.
But a source close to the shortlisted consortiums said the announcement could slip further. "There have been lots of to-ing and fro-ings between [Highways Agency chief executive] Archie [Robertson] and the Treasury and the date could slip again."