“Based on the evidence we’ve seen so far, as set out in our objections, we believe that the actions of the N.L.R.B. and the A.L.U. improperly suppressed and influenced the vote, and we think the election should be conducted again so that a fair and broadly representative vote can be had,” Kelly Nantel, an Amazon spokeswoman, said in a statement.

In another objection, the company said the union had failed to file standard financial reports. In an interview with The Times this week, Christian Smalls, president of the union, said it had supplied needy workers with cash, both through separate GoFundMe efforts and the union’s funds.

If a worker needed her bills paid, “we’re paying that bill, we’re sending money right over no question,” Mr. Smalls said. Legal experts said that some of those transactions — such as extra pay for union organizers out sick with Covid-19 — might be fine but that others could cause problems depending on when and how many people received them.

But the N.L.R.B. “rarely” overturns elections on allegations of union misconduct, said John Logan, a professor at San Francisco State University who studies employer campaigns. Amazon will need to prove that any objectionable conduct could have altered the result of the election, he said, and “unlike Amazon, the A.L.U. has no coercive power over employees.”

The labor agency granted Amazon a two-week extension, to April 22, to provide additional evidence supporting the objections.

In Bessemer, Ala., the union trailed slightly in the initial tally of the votes announced on March 31: 993 workers voted against being represented by the Retail, Wholesale and Department Store Union, and 875 voted in favor. But more than 400 ballots have yet to be counted because they were challenged by either party. Those challenged ballots, enough to potentially affect the outcome, are set to be resolved at a labor board hearing in the coming weeks.

The election this year was a do-over that the labor board had ordered after siding with the union’s claims that Amazon illegally interfered with an election at the facility last year.