A hearing officer of the National Labor Relations Board has recommended that the board throw out a union election at an Amazon warehouse in Bessemer, Ala., where results announced in early April showed workers rejecting a union by a more than two-to-one ratio.
The union announced the recommendation on Monday, and Amazon quickly said it would take steps to ensure that the original election result prevailed.
The hearing officer’s recommendation, which includes holding a new election, will be reviewed by the acting regional director of the agency, who will issue a ruling on the case in the coming weeks. If the regional director rules against Amazon, the company can appeal to the labor board in Washington.
The union campaign at the warehouse, which had more than 5,000 eligible workers, was the highest-profile domestic organizing effort so far at Amazon, which has a history of aggressively deterring worker activism.
The challenge by the union, the Retail, Wholesale and Department Store Union, accused Amazon of engaging in unfair labor practices to keep workers from unionizing.
“Throughout the N.L.R.B. hearing, we heard compelling evidence how Amazon tried to illegally interfere with and intimidate workers as they sought to exercise their right to form a union,” said Stuart Appelbaum, the union’s president, in a statement. “We support the hearing officer’s recommendation that the N.L.R.B. set aside the election results and direct a new election.”
The union first filed paperwork for the election in November, and the voting took place by mail between early February and late March.
The union complained frequently during the campaign that the company was intimidating and threatening workers.
Amazon disputed the accusations and continues to do so.
“Our employees had a chance to be heard during a noisy time when all types of voices were weighing into the national debate, and at the end of the day, they voted overwhelmingly in favor of a direct connection with their managers,” an Amazon spokeswoman said in a statement on Monday. “Their voice should be heard above all else, and we plan to appeal to ensure that happens.”
Wilma B. Liebman, who was chairwoman of the labor board under President Barack Obama, said regional directors typically followed the recommendations of hearing officers in such cases.
About one week after the labor board announced the results in April, the union filed a formal objection to the conduct of the election and asked the board to overturn it. An officer for the board held hearings over three weeks in which both sides called and questioned witnesses.
The union objection contended that Amazon consultants and employee relations managers had created an atmosphere of fear by identifying and removing workers from mandatory anti-union meetings if they questioned company officials, and by telling employees they risked losing pay, benefits or even their jobs if a union was established.
The union also contended that Amazon consultants and managers had illegally asked workers how they intended to vote, and that Amazon fired a union supporter for distributing union cards. It said the company took several measures — such as increasing pay and giving away merchandise — to defuse pressure for a union. It is illegal to begin to take such steps once a union campaign is underway.
The union objection focused heavily on an on-site collection box that Amazon had repeatedly pushed the U.S. Postal Service to install shortly before the voting began. The union said the box was not authorized by the labor relations board. Amazon has said that it pushed for the box to make it easier for employees to vote and that it did not have access to ballots that workers placed inside.
The union argued that the presence of the collection box gave workers the impression that Amazon was monitoring who voted, and possibly even how they voted.
It is not clear whether the union would improve its showing if the election were rerun. Labor law allows companies to hold frequent mandatory anti-union meetings, and Mr. Appelbaum, the retail workers’ president, has said that high turnover at the warehouse was a significant obstacle to the union campaign.