California-based construction and civil engineering firm Bechtel has been chosen as the preferred bidder to become the development partner for HS2 Phase 2b.
The standstill period will now last for two weeks before the contract is officially signed by Bechtel. It is understood that Mace will still be able to legally challenge the decision within this window.
Stop HS2 campaign manager Joe Rukin said: "CH2M walked away from one contract due to conflict of interest, hoping no-one would notice they still have the contract that gives them a massive say in where £8.6bn of Phase 1 construction contracts go".
"The withdrawal of CH2M from a major HS2 contract raises several questions which must be answered".
Keep up to date as Sir David Higgins and Chris Grayling face questions tomorrow on HS2 procurement with CN's live blog.
Phase 2a from the West Midlands to Crewe will open in 2027 and Phase 2b from Crewe to Manchester and Birmingham to Leeds, will begin operation in 2033.
CH2M chose to pull out of the procurement process at the end of last month after one of the losing bidders, Mace, threatened a legal action against the competition, commenting that it had "never seen a procurement process like this". CH2M executive Roy Hill had also been seconded to HS2 as interim chief executive after the resignation of Simon Kirby.
Construction News also revealed that HS2 was understood to be looking into the part played by former HS2 chief of staff Christopher Reynolds in the U.S. engineering giant's tender for the deal.
An HS2 spokesperson said: "HS2 Ltd can confirm that Bechtel are being taken forward to the next stage of the 2b Development Partner procurement process. Following discussions, we are confident they are able and prepared to deliver the contract on time, on budget, and to a high standard".