Amazon workers at a second Staten Island warehouse have voted against joining the Amazon Labor Union, a blow to the organizing efforts at the e-commerce company one month after employees at a larger warehouse in the area approved unionization.

The National Labor Relations Board said Monday that 62% of workers who cast valid ballots at the LDJ5 warehouse voted not to form a union, in a 618-to-380 tally. Amazon Labor Union was started by former Amazon supervisor Chris Smalls, who said he was fired for trying to organize his coworkers.

It is led by current employees, who wanted to spark a movement that would spread to other Amazon warehouses. Amazon, which is challenging that earlier April vote, has said it prefers negotiating directly with employees. The company tried to persuade employees to vote no on the union.