On Sunday night, President Joe Biden released a message of support for unionizing Amazon workers in Alabama, while sternly denouncing anti-union efforts by employers.

The message comes in the midst of a contentious union election at an Amazon warehouse in Bessemer.

And while Biden stopped short of an explicit endorsement of the fledgling Bessemer union, he was broadly enthusiastic about the benefits of collective bargaining.

“I made it clear during my campaign that my policy would be to support unions organizing and the right to collectively bargain,” Biden said in the statement. “I’m keeping that promise.”

It’s rare for a sitting president to publicly support a union drive, and the statement is careful not to direct workers to vote in favor of unionization, as such statements might violate labor law.

Biden never names Amazon directly in the statement, although he does directly name Alabama warehouse workers. He also denounces anti-union efforts in a way many will see as aimed at the company.

“There should be no intimidation,” Biden says in the video, “no coercion, no threats, no anti-union propaganda.”

The Retail, Wholesale and Department Store Union (RWDSU), which is organizing the Bessemer worksite, applauded the statement.

“As President Biden points out, the best way for working people to protect themselves and their families is by organizing into unions,” said RWDSU president Stuart Appelbaum in a statement.

“And that is why so many working women and men are fighting for a union at the Amazon facility in Bessemer, Alabama.”

Amazon has been aggressive in its efforts to prevent the warehouse from unionizing, inundating Alabama workers with text messages and worksite posters warning of the downsides of unionization.

Last week, workers spotted anti-union ads running on Amazon-owned Twitch, although Twitch withdrew the ads once their existence was made public. 

In another incident, Amazon worked with county officials to alter the timing on a stoplight near the warehouse, making it harder for organizers to approach workers as they left the site.

In some instances, those efforts have provoked a backlash against the company.

Last week, Amazon’s VP overseeing labor and employment law abruptly resigned from the American Constitution Society, a liberal legal group that had recently appointed him to a three-year term.

A coalition of members had called for his resignation in December, citing Amazon’s response to a walkout at a Staten Island warehouse last year.

Amazon did not immediately respond to a request for comment.