The shortlisted bidders for the 4km road are: Balfour Beatty Civil Engineering, Farrans Construction/Roadbridge, Interserve Construction and John Paul Construction/Somague Engenharia.
The contract for the Dalry Bypass project is estimated to be worth between £34m and £38m and involves the construction of the new bypass and associated junctions to connect to the existing A737 trunk road.
Scotland transport minister Humza Yousaf said: "This announcement marks another significant milestone for the Dalry Bypass. It ensures we remain on schedule to appoint a contractor early next year and for works to start on this critical infrastructure project by the end of March 2017.
"The new road will be a key driver in improving economic and employment opportunities in the area by providing better journey time reliability and enhancing connectivity. It will also improve safety by taking traffic away from unsuitable roads."
Somague Engenharia is a Portuguese contractor that is currenty working in joint venture with Lagan Construction on a £150m contract for Ulster University’s new Belfast campus.