The Teamsters Local Union 853 reported workers at the Google Express shopping service employed by Adecco have filed a request for representation.
Google Express ships products from local consumers to businesses on a same-day or overnight basis. The union said workers sign an agreement that limits them to two years on the job.
The unionization request includes more than 140 warehouse and shipping workers.
An Adecco spokeswoman told USA Today that they have not received complaints from the workers on working conditions.
Earlier this month, the National Labor Relations Board invited interested parties to file briefs regarding whether it should permit bargaining units comprised of both regular employees and temporary workers provided by a staffing agency to form without employer approval.