Section 4. Call of convention. If a majority of those voting on the question answer in the affirmative, the legislature shall provide for the calling thereof at its next session. The number of delegates to the convention shall be the same as that of the larger body of the legislature. The qualifications of delegates shall be the same as the highest qualifications required for election to the legislature. The legislature shall determine whether the delegates may be nominated on a partisan or a non-partisan basis. They shall be elected at the same places and in the same districts as are the members of the legislative body determining the number of delegates.