United Parcel Service Inc.’s union workers will hold a vote on whether to grant authorization to Teamsters’ leaders to call a strike after the current five-year contract lapses.

The results of the vote, which is typical in labor discussions to give negotiators a stronger hand, will be announced on June 16, according to a Teamsters memo to members. The labor contract, which expires July 31, covers more than 340,000 UPS workers.

“The time has come to use our strongest leverage and officially remind UPS that hundreds of thousands of Teamsters are ready to withhold our labor to ensure UPS acts accordingly,” Sean O’Brien, Teamsters president, said in the memo.

While unionized pilots for several airlines and rival FedEx Corp. have announced votes for strike authorizations, those companies are governed by the Railway Labor Act, which creates several barriers to a strike, including allowing Congress to intervene directly. That’s not the case with the workers covered by this latest UPS vote, which does not include the company’s pilots. If the strike authorization is approved, O’Brien could call for a walkout as soon as Aug. 1.

UPS said in a statement that it continues to make progress in the negotiations.

“This vote is a routine part of the bargaining process and does not mean that there will be a strike,” UPS said in the emailed statement.