Amazon workers on Staten Island show they have enough support to hold a union election.

A fledgling union of employees at four Amazon warehouses on Staten Island demonstrated on Monday that they had enough worker interest to hold an election to form a union, the National Labor Relations Board said. The agency’s determination lays the groundwork for the second unionization vote at an Amazon warehouse in less than a year.

For months, the organizers behind the union push have been collecting signatures on cards that must be submitted to the labor agency to request a vote. Christian Smalls, a former Amazon employee leading the effort, said late last week that he anticipated submitting more than 2,000 employee signatures, though he declined to disclose the final count.

The labor board determined that the submission represents at least 30 percent of the proposed bargaining unit, according to Kayla Blado, the press secretary for the labor board. In the coming days, Amazon must notify workers at the facilities via text notifications and signage of the union petition, and the agency will hold a hearing in mid-November, where Amazon can contest which jobs should be included in the bargaining unit and the terms of the election.

“I have no doubt in my mind that we’re good,” Mr. Smalls said.

Amazon was “skeptical that a sufficient number of legitimate employee signatures has been secured to warrant an election,” Kelly Nantel, a company spokeswoman, said in a statement. “If there is an election, we want the voice of our employees to be heard and look forward to it. Our focus remains on listening directly to our employees and continuously improving on their behalf.”

The Staten Island effort is being organized by current and former Amazon workers aiming to form a new independent union, called the Amazon Labor Union, focused solely on the nation’s second-largest employer.

An election at an Amazon warehouse in Alabama early this year, supported by a national retail workers union, was unsuccessful. But the labor agency is considering throwing out the results of that election because of Amazon’s anti-union measures. Amazon has said it would appeal if the vote is invalidated.

Monday’s submission is the result of six months of organizing focused on a massive Staten Island warehouse, known as JFK8, that serves as Amazon’s key pipeline to New York City and employs more than 5,000 people. Over time, the organizers extended their push to include three smaller Amazon facilities in the same industrial park.

Workers at JFK8 have accused Amazon of illegally interfering with their organizing rights. Staff lawyers at the labor board have found some merit to further pursue three of their cases and is still investigating six additional cases, the agency said.