N.D. Cent. Code § 24-02-23

Each and every contract in excess of the sum specified in section 24-02-17 must be awarded by the department to the responsible bidder submitting the lowest and best bid, but said department may reject all bids. If no satisfactory bid or bids are received, new bids may be called for. The successful bidder must be required to furnish a suitable bond in at least the amount of the contract and with such surety as may be determined by the department and as approved by it.