N.J. Stat. § 27:7-31
A proposal bond in an amount, not to exceed 50% of the bid, to be determined by the commissioner, executed by the contractor with such sureties as shall be approved by the commissioner in favor of the State of New Jersey, shall accompany each bid and shall be held as security for the faithful performance of the contractor in that, if awarded the contract, the bidder will deliver the contract within 10 working days after the award, properly executed and secured by satisfactory bonds in accordance with the provisions of N.J.S. 2A:44-143 to N.J.S. 2A:44-147 and specifications for the project. The commissioner may require in addition to the proposal bond such additional evidence of the ability of a contractor to perform the work required by the contract as the commissioner may deem necessary and advisable.
N.J.S. § 27:7-31