Sen. Bernie Sanders, one of the labor movement’s most vocal champions in Congress, is planning to visit Amazon workers in New York City on Sunday as a second Staten Island warehouse prepares to vote on whether to form a union.

Voting at the 1,500-employee LDJ5 facility, which is located across the street from the JFK8 warehouse that scored a historic union win earlier this month, is set to begin on April 25, a day after Sanders’ (I-Vt.) planned visit.

Christian Smalls, president of the Amazon Labor Union (ALU)—the independent, worker-led organization leading the unionization efforts at the e-commerce giant—announced the Vermont senator’s visit in a tweet on Wednesday.

On the day of Sanders’ visit, ALU is planning to hold a rally near LDJ5 to show support for the unionization effort at the Staten Island facility. Sara Nelson, president of the Association of Flight Attendants-CWA, and Mark Dimondstein, president of the American Postal Workers Union, are among those expected to appear at the rally.

“Unionization at Amazon holds a special significance for postal workers who work in the same mail/package/delivery industry. When one group of workers rises, we all rise,” Dimondstein said in a statement following the victory at JFK8 earlier this month.

“The APWU stands ready to assist the newly organized workers in Staten Island in any way we can in the coming and challenging battle to win a good first union contract,” Dimondstein added, “and stands ready to work with all Amazon workers and all unions in building Amazon workers’ power at Amazon.”

During an organizing call last week, Sanders expressed his view that ALU’s victory at JFK8 has the potential to spur “a national, sweeping movement” of unionization at Amazon—a corporation notorious for mistreating its employees—and other companies across the United States.

According to Smalls, employees at more than 100 Amazon facilities reached out to ALU about organizing their workplaces in the wake of the JFK8 win. In Bessemer, Alabama, meanwhile, the Retail, Wholesale, and Department Store Union (RWDSU) is accusing Amazon of unlawful interference during a recent union election, which was too close to call.

“All across this country, people are saying, ‘Whoa! If these guys at Amazon can take on that company, we can do it as well,’” said Sanders, the chair of the Senate Budget Committee. “People are sick and tired of corporate greed.”

While ramping up its union-busting campaign ahead of the LDJ5 vote, Amazon is also formally objecting to the JFK8 election in a bid to overturn the results. The company has until Friday to file evidence of its allegations with the National Labor Relations Board.

Among Amazon’s claims are that ALU “engaged in electioneering in the polling area” and “distributed marijuana to employees in exchange for their support.” The company also asserted that ALU’s “members and agents harassed and threatened physical violence and other reprisals against employees who were not supportive” of unionization, an accusation that ALU attorney Eric Milner emphatically rejected.

“To say that the Amazon Labor Union was threatening employees is really absurd,” Milner told Reuters earlier this month. “The Amazon Labor Union is Amazon employees.”