In an election that was watched closely nationally and internationally, a union of retail store workers has failed in its effort to organize the close to 6,000 employees of tech giant Amazon in Bessemer, Alabama.

Given President Biden’s strong support of the union movement generally, and of the Amazon workers in Bessemer specifically, it was a stinging defeat for his administration and for the union movement.

The lopsided vote was 738 in favor of joining the union, and 1,798 against. Seventy-six ballots were voided, and there are pending challenges to 505 ballots. The challenges, if sustained, are not sufficient in number to affect the results of the election.

The election and the ballot count were supervised by the National Labor Relations Board (NLRB), an independent federal agency established in 1935, based in Washington, D.C., that enforces federal labor laws.

Approximately 3,041 Amazon employees (about a 55% turnout), mailed in ballots indicating whether or not they wanted to be represented by the New York-based Retail, Wholesale and Department Store Union at the Amazon facility, which is located 17 miles southwest of Birmingham.

The retail union said it is filing a legal challenge to the election, and charges of unfair labor practices against Amazon. It is requesting a hearing by the National Labor Relations Board “to determine if the results of the election should be set aside because conduct by the employer created an atmosphere of confusion, coercion and/or fear of reprisals and thus interfered with the employees’ freedom of choice.”

Amazon rejected the union’s allegations Friday, adding: “Amazon didn’t win — our employees made the choice to vote against joining a union.”

“This particular union can’t give us anything that Amazon does not already offer,” said LaVonette Stokes, a Bessemer worker who voted against unionizing. “There are a [lot] of people who never have issues.”

Ms. Stokes, who started work at the Bessemer warehouse last July, said the union had failed to convince the workers how it could improve their working conditions. Amazon already provides good benefits, relatively high pay that starts at $15 an hour, and opportunities to advance, said Ms. Stokes, who has five children.

“Amazon is the only job I know where they pay your health insurance from Day 1,” Ms. Stokes, 52, said. She added that she had been turned off by how organizers tried to cast the union drive as an extension of the Black Lives Matter movement because most of the workers are Black. “This was not an African-American issue,’’ said Ms. Stokes, who is Black. “I feel you can work there comfortably without being harassed.”

The historic Deep South election was one of the highest profile clashes to date between the anti-union company and organized labor. Pro-union workers at the facility said they wanted a bigger say in how the high-pressure workplace operates. Amazon argued that its $15-an-hour starting wage and benefits package is appropriate, and already covers what unions typically demand.

Union advocates argued that Amazon demands a dehumanizing pace of work, putting employees under intense mental and physical stress. Given that the company has reaped enormous profits during the pandemic, the union proponents want to see that translate to higher pay for workers who have continued to fill orders throughout the crisis.

The union push in Bessemer gathered the attention of sports stars, politicians, and celebrities. Actor Danny Glover, a group of House Democrats, and longtime Amazon critic Sen. Bernie Sanders came to visit. Black Lives Matter organizers stood in solidarity. Endorsements arrived from politicians, including the president and Republican Florida Sen. Marco Rubio.

In a newspaper opinion column, Sen. Rubio wrote: “When the conflict is between working Americans and a company whose leadership has decided to wage culture war against working-class values, the choice is easy — I support the workers. And that’s why I stand with those at Amazon’s Bessemer warehouse.”

In European countries including France, Italy, Spain, and Germany, where union membership is far more widespread and barriers to entry are substantially lower, Amazon workers have long been unionized.

Amazon executives have long resisted unions over stated fears that the company might find itself hamstrung by workplace rules that could limit technical innovations such as the use of robots Amazon management also worry that unionization could slow their expansion plans, forcing the company to negotiate the terms of hiring and laying off staff, as well as the number of temporary workers it could take on.