A race for a selectmen’s seat is the only contest on the ballot of the May 18 annual town election. Incumbent David W. Soper faces a challenge from Kenneth A. Mitchell Sr., a member of the search committee for the new police chief. Candidates are running unopposed for 14 seats, including incumbent Susan McSweeney and Donald L. Ford, Jr., the only two contenders for two seats on the Whitman Hanson Regional School Committee. Four seats did not attract any ballot candidates. A special election on whether to recall Board of Health member Tom T. Constantine will be held on a separate ballot May 18. The election, which resulted from a citizen petition, asks whether Constantine should be recalled and who should fill that seat if the recall succeeds. The two candidates under the second question are Constantine and Gilbert B. Amado, a former Board of Health member.