Five bidders are competing for a £20m upgrade of the A75 from Hardgrove to Kinmount.
The five companies bidding are McLaughlin & Harvey, Balfour Beatty Civil Engineering, John Paul Construction, I & H Brown and RJ McLeod.
The work will involve building just over two miles of new road to provide alternating overtaking facilities in both directions.
Transport Minister Keith Brown said: “The Scottish Government has been clear in its commitment to improving the A75 and we welcome this keen interest from the construction industry.
“It is through projects such as this that we can support employment opportunities during the construction phase while providing benefits for road users.
“Together with A75 Dunragit Bypass and A77 Symington to Bogend Toll schemes announced in July, we can clearly demonstrate our very real efforts to improve connectivity and make Scotland an attractive option for business, leisure and tourism.”
Construction is expected to start in 2013 and be completed in 2014.