StarbucksThe campaign to discourage baristas unionizing might include the extension of new benefits only to workers who are not members. the Wall Street Journal reported Wednesday.

According to the Journal, Howard Schultz, CEO of the company, told U.S. store managers this week that he was reviewing the benefits program for the chain’s workers. According to Schultz, however, those employees working in company-owned shops that have voted to unionize will not be eligible for these improved benefits.

Schultz quoted federal labor law and counsel from the company’s lawyer in stating that it would be illegal to grant benefits unilaterally to unionized locations within the equation. The Journal reported.

Federal labor law requires employers to reach an agreement with workers’ unions regarding changes to their terms and conditions of employment, such as compensation or benefits. However, companies have the right to ask employees who are unionized for additional benefits.

U.S. airlines are, by example, highly unionized. Union employees have been offered bonuses and additional pay to alleviate staff shortages. This is an incentive that falls outside regular contract negotiations.

CNBC reached Starbucks for comments but did not receive a response immediately.

Starbucks Workers United stated that it was expecting the company to announce new benefits in order to stop the growing union pressure at Starbucks. This announcement came just a few days before Schultz returned to the company. Starbucks’ representative did not return a request to comment. However, Schultz announced that last week he would stop stock buybacks in order to make more investments back in the workers.

About 200 Starbucks stores that are company owned have recently filed paperwork to unionize. Up to date, 18 Starbucks stores have voted for unionization under Workers United. Only one café voted against.

Workers United is claiming that Workers United engaged in anti-union activities, such as firing workers, cutting hours at unionizing sites, and other forms of retaliation. The NLRB brought a lawsuit against Starbucks in March alleging it had violated federal labor laws by firing organizers from a Phoenix office.

Schultz is already waging an aggressive campaign against the union in his first week back as CEO of the company than Kevin Johnson. Schultz made mention of the union in letters and talks with workers. He called the move to organize unnecessary and divisive.

“And while not all the partners supporting unionization are colluding with outside union forces, the critical point is that I do not believe conflict, division and dissension – which has been a focus of union organizing – benefits Starbucks or our partners,” he wrote in a letter to employees on Sunday.

Starbucks stock shares rose more than 1% on Wednesday, along with wider market gains. It has an approximate market value $93.3 billion.

Read the Journal’s report on Schultz’s strategy to tackle the union push.

—CNBC’s Leslie Josephs contributed to this report.