Washington (CNN) -- The runoff vote to determine which union will represent the 40,000-plus airport screeners will begin May 23, the Federal Labor Relations Authority said Thursday.
The election will be conducted over a four-week period ending on June 21. The votes will be tallied and announced on June 23, the agency said.
In the initial six-week voting process, neither union seeking to represent the transportation security officers received a majority.
The American Federation of Government Employees received 8,369 votes and the National Treasury Employees Union received 8,095, while workers cast 3,111 votes to reject a union, according to unofficial results released by the Labor Relations Authority on Wednesday.
The choice of no union representation will not appear on the ballot for the runoff, so a simple majority will decide the winner.