Officers and employees of the political subdivision who are regularly employed full time on a salaried basis and whose tenure is not restricted as to temporary or provisional appointment may become members of the retirement system. Clerks of the circuit court and deputies shall be included in the coverage group. Officers and employees of an organization other than a public school board that functions solely within the boundaries of a county, city, or town shall be deemed to be officers and employees of the county, city, or town, and not of the organization, unless the cost of the organization’s operation is borne by (i) the users of services, (ii) more than one county, city, or town, or (iii) any entity other than a county, city, or town. A member of a local system who, through election to a position as a constitutional officer, is no longer eligible for membership in the local system, and who, prior to such election, has accumulated within that system more than half the total service credits necessary to become eligible for full normal retirement benefits, may choose, with the concurrence of the local governing body, (i) not to participate in the retirement system established pursuant to this chapter and (ii) to become a member of the local system. In such case, the member shall be deemed, for retirement purposes only, to have ceased employment, and shall be permitted to withdraw his contribution as provided in § 51.1-161.