The union representing Jefferson City bus drivers could call a strike.
Parents of children in summer school have been alerted to prepare for the possibility of no school bus service during summer school.
The Teamsters Union is in a dispute over wages with First Student, the Ohio-based company that provides the transportation service.
The union wants capital city drivers to earn the same amount their counterparts in Columbia do.
At the beginning of June, local drivers rejected the company's offer.
"I don't wanna strike, Teamsters Local 833 member Mark Bruemmer said. But, as bad as it is, when they impose a last, best, final offer, that's the only ammunition I have right now to try to get parity between Columbia and Jeff City.
The summer program for elementary students runs through June 29.
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