CNN Business  — 

Six months after the grassroots Amazon Labor Union scored a historic victory by becoming the first to unionize one of the tech giant’s US facilities, it now appears to be grappling with setbacks and delays.

Workers at a California Amazon facility withdrew their petition late last week to unionize with the ALU, just days after the labor group failed to win enough votes to unionize an Amazon facility in upstate New York.

Kayla Blado, a spokesperson for the National Labor Relations Board, confirmed to CNN Business on Tuesday that the petition for a union election at the ONT8 facility in Moreno Valley, California, had been withdrawn. Blado added that the petitioner does not have to provide a reason to the NLRB for doing so. The move to withdraw comes roughly two weeks after the petition was submitted, per the NLRB’s docket of the case.

In an email to CNN Business, ALU President Chris Smalls played down the significance of the withdrawn petition. “The withdrawal isn’t nothing to worry about,” he said. “We will be refilling within the next few weeks just as we did with our JFK8 campaign,” Smalls added, referring to the name of the unionized facility in Staten Island, New York.

Smalls did not offer a reason for the decision to withdraw and potentially refile the petition.

Since the watershed union win at JFK8, the ALU hasn’t seen success with organizing efforts at other Amazon facilities. In addition to the Amazon workers near Albany voting against joining the union last week, the ALU also failed to win enough votes to unionize a smaller Amazon outpost in Staten Island.

Moreover, Amazon has refused to recognize or meet with the union at JFK8 — and continues to challenge the union’s election win. Labor experts say the saga reveals how difficult it is to organize a union under current labor laws.

Amazon has long maintained that it prefers working with employees directly, versus through a union. After the workers near Albany voted against forming a union, an Amazon spokesperson said the company is “glad” to see “they chose to keep the direct relationship with Amazon as we think that this is the best arrangement for both our employees and customers.”

Despite the uphill battle the union faces, Smalls previously told CNN Business that he sees the increase in organizing efforts at Amazon facilities across the country as its own victory.

“The expansion of the ALU is definitely historical by itself,” Smalls said. He added that the group has been fielding an explosion of interest from Amazon workers across the country since the ALU’s original win in Staten Island in April.