Except as to elected constitutional officers, the Governor may make such changes in the organization of offices, boards, commissions, agencies and instrumentalities, and in allocation of their functions, powers and duties, as he considers necessary for efficient administration. If such changes affect existing law, they shall be set forth in executive orders, which shall be submitted to the Legislature within five legislative days after it convenes, and shall become effective, and shall have the force of law, within ninety days after submission, unless disapproved by a resolution concurred in by a majority of all the members of either house.