Mo. Rev. Stat. § 115.051: County clerk may employ election staff and fix compensation.

1. In each county which does not have a board of election commissioners, the county clerk shall have the right to employ such deputies and assistants as are necessary to promptly and correctly register voters and conduct elections. Where an electronic voting system or voting machines are used, the county clerk shall designate competent employees to have custody of and supervise maintenance of the voting equipment. Each deputy shall be subject to the same restrictions and subscribe the same oath as the county clerk, except that no employee shall be required to post bond or reside and be a registered voter within the jurisdiction of the election authority unless directed to do so by the clerk. Employee oaths and any bonds shall be filed and preserved in the office of the county clerk.

2. Within the total amount for deputies and assistants approved by the county commission, the salary of each deputy and assistant shall be set by the county clerk.