Teamsters union members at some local bargaining units again rejected parts of their contract with United Parcel Service Inc., prolonging the package and delivery giant's labor headaches as it enters the busy holiday season.

In a vote on Thursday, Teamsters-represented workers at UPS rejected two of seven supplements or riders to the master contract, further delaying ratification of a deal that was approved last summer.

Members of a dozen locals in Ohio rejected a rider by a vote of 2,189 to 1,805, while Local 623 in Philadelphia rejected a supplement by a vote of 781 to 332.

The remaining five ballot initiatives passed, however, including the largest, the Central Region supplement, which covered swaths of the Midwest and with Teamsters Local 89. The latter local represents about 10,000 UPS employees who work at or near UPS's giant automated packaging hub in Louisville, Ky. The Central Region supplement passed by 11,599 votes to 10,006.

The supplements and riders involve issues the company must resolve with individual local bargaining units on issues like health-care benefits, wages for part-timers and overtime pay.

UPS still has a lot more work to do before it can complete this round of labor talks with the Teamsters. Though the master contract was approved in June, it won't take effect until all of the supplements and riders are negotiated separately with the union's local bargaining units and approved by them.

A UPS spokesman said: "We continue to make progress and will continue to work with the Teamsters to finalize the remaining contracts."

If any supplements are rejected, they must be renegotiated with the union locals, according to Fred Zuckerman , president of Local 89. After this round of supplements, there are nine more outstanding that haven't yet been voted on, according to a union spokesman. UPS and the Teamsters agreed to indefinite contract extensions to resolve remaining issues.

UPS wanted to get the labor issues settled last summer before the last master contract expired. Customers are spooked by ongoing labor negotiations, fearing they can lead to possible slowdowns or disruptions.