Profits at UPS fell year-over-year in the second quarter as the parcel carrier lost more business to rivals than expected due to uncertainty surrounding negotiations with the Teamsters.

Local union leaders voted in favor of a tentative labor agreement that UPS and the Teamsters reached July 25, an important step toward finalizing a deal that covers about 340,000 workers.

Some large retailers and other companies across the country are warning customers of potential delivery delays if there is a UPS strike.

A potential strike by 340,000 unionized workers at UPS Inc. threatens to unravel progress in tackling two of the U.S. economy’s biggest hurdles: inflation and supply chain disruptions.

UPS Inc. and its union will resume labor talks July 25 after negotiations had stalled earlier this month as the company seeks to head off a strike that could occur as early as Aug. 1.

The pilots union at Sandy Springs, Ga.-based UPS Inc. plans to honor picket lines in the event of a Teamsters strike against the shipping giant.

UPS Inc. plans to train nonunion employees to deliver packages in the event of a labor disruption in the U.S., underscoring the potential for a strike as a crucial negotiating deadline nears.

UPS Inc. investors will wait longer than usual to hear from CEO Carol Tomé this quarter as the company works to avoid a harmful worker strike.

A strike by UPS workers if a new labor agreement isn’t reached with the Teamsters would hold significant implications across the supply chain, industry analysts said.

Negotiations on a new labor deal between UPS Inc. and the Teamsters stalled July 5 after showing promise over the weekend, renewing concern that workers could strike at the end of the month.