Does a deputy have to resign from his duties if he is running for office?

The Constable in office now was appointed by the commissioners not elected by the community because the previous Constable resigned before his term was over due to medical conditions. If a deputy from that same precinct wants to run against the appointed constable, does that mean he must resign from his duties? Do you need to be commissioned through TCLEOSE in order to run for an elected position (Constable)?