Since unionization efforts began at three Buffalo Starbucks (SBUX  ) locations last August, labor organizing has spread through the chain, resulting in roughly 250 stores joining the union, Workers United. Now, that rush to hold union votes is receding, and organizers are entering a new phase of collective bargaining.

While the union initially seemed to take Starbucks by surprise, the coffee giant quickly invested in a massive campaign to combat organizing at its 9,000 locations, and it has been fighting back hard against the stores that successfully held votes.

Along with swarming stores with anti-union corporate officials, Starbucks has also introduced wage increases and new benefits that only apply to non-union workers, has closed unionized locations, and has been firing workers for their involvement with the union. These tactics have resulted in several National Labour Relations Board (NLRB) complaints being filed and upheld against the chain.

Starbucks' work to discourage organizing has also contributed to a drop-off in election filings, from around 70 in March to fewer than 10 in August.

"Stores that are easy to organize, that had people in them who were natural leaders, who were excited about it - those have filed already," a former Starbucks employee and organizer, Brick Zurek, told reporters.

Starbucks is attempting to overthrow and reverse votes where possible, but experts say the company won't be able to fully reverse the union's work. Still, out of all of Starbuck's corporate-owned stores, only a tiny portion has joined the union.

"Anyone who thinks it's going back anywhere close to zero is foolish. It's safe to assume they'll have at least hundreds of cafes unionized going forward," David Pryzbylski, a partner at the management firm Barnes & Thornburg, said. "In the context of the size of the organization as a whole, it's a drop in the bucket."

With what power they do have, officials with Workers United have been trying to get Starbucks to agree to certain concessions, including a pledge to stay neutral in future union votes. The union is also bargaining for paid leave for pandemic absences.

Stopping the company from campaigning against unionizing would be a big win for organizers, and successfully bargaining for paid leave could also show workers that voting for the union is worth it.

Still, experts say that negotiation alone won't be enough to get the concessions the union wants. Workers will most likely need to put pressure on the company through strikes and other forms of protest, as well.

The union only includes a fraction of all Starbucks stores, but many unionized stores are concentrated in metropolitan areas, like Eugene, Oregon; Albany, New York; and Ann Arbor, Michigan, making it easier for workers to organize effective protests in those areas.

"Massing forces in a particular geographic region and attempting to spread the conflagration there has the potential to work," Peter Olney, a former organizing director of the International Longshore and Warehouse Union, told The New York Times. "I would focus on those metro areas."