In addition to the provisions of § 4a-60, every public works contract, municipal public works contract or contract for a quasi-public agency project subject to the provisions of part II of chapter 60 shall also be subject to the provisions of this section. After a bid has been accepted but before a contract is awarded, the successful bidder shall file with and have obtained the approval of the executive director or the executive director’s designee for an affirmative action plan. The executive director or the executive director’s designee may provide for conditional acceptance of an affirmative action plan provided written assurances are given by the contractor that it will amend its plan to conform to affirmative action requirements. In the case of a public works contract, the state shall withhold two per cent of the total contract price per month from any payment made to such contractor until such time as the contractor has developed an affirmative action plan, and received the approval of the executive director or the executive director’s designee. In the case of a municipal public works contract or contract for a quasi-public agency project, the municipality or entity, as applicable, shall withhold two per cent of the total contract price per month from any payment made to such contractor until such time as the contractor has developed an affirmative action plan and received the approval of the commission. Notwithstanding the provisions of this section, a contractor subject to the provisions of this section may file a plan in advance of or at the same time as its bid. The executive director or the executive director’s designee shall review plans submitted pursuant to this section within sixty days of receipt and either approve, approve with conditions or reject such plan. When the executive director or the executive director’s designee approves an affirmative action plan pursuant to this section, the executive director or the executive director’s designee shall issue a certificate of compliance to the contractor as provided in § 46a-68c.