SEATTLE — The National Labor Relations Board on Wednesday rejected Amazon’s bid to delay a hearing on the union drive of Alabama workers into January, as the e-commerce giant signals its willingness to vigorously battle employees trying to organize.

Bessemer warehouse workers notified the NLRB last week that they want to hold an election to create a bargaining unit that would cover 1,500 full-time and part-time workers, represented by the Retail, Wholesale and Department Store Union (RWDSU). The agency had scheduled a Dec. 11 hearing to determine, among other items, whether to call a union election.