Alternatively, instead of presenting the measure to the Governor, the Legislature may order that it be submitted to the people. If the measure is approved by the people, the Governor has no power to veto it, and the Legislature may not repeal it, and may not amend it unless the amending legislation furthers the purposes of such measure and at least three-fourths of the members of each house of the Legislature, by a roll call of ayes and nays, vote to amend such measure.