Thousands of Teamster UPS drivers across the United States are expected to authorize a strike Friday, bringing the country a step closer to what would be among the largest work stoppages in decades.

An authorization vote does not mean that a strike will happen, but it gives Teamsters union leaders the right to call for a national walkout if a contract deal is not reached in negotiations before July 31. It would be the first strike to threaten the nation’s transportation infrastructure system since the last time UPS employees went on strike 26 years ago and the largest of any industry since the 1950s.

UPS and the International Brotherhood of Teamsters have been in talks since early May over the UPS contract, which sets pay, benefits, and working conditions for some 340,000 UPS employees nationwide. The major sticking points are over-raising pay, the creation of more full-time jobs, and eliminating UPS’s reliance on a lower-paid class of delivery driver.

The negotiations could have sweeping implications for the U.S. labor movement and the economy. For decades, the UPS Teamsters contract has set and raised standards for workers around the United States, ensuring a path to the middle class for many Americans without college degrees. Meanwhile, a strike could have devastating consequences for an economy that is increasingly reliant on its delivery infrastructure, with an estimated 6% of the country’s gross domestic product passing through UPS delivery vans each year.

Leading the contract fight is Teamsters Union president Sean O’Brien, whose rise to the top job ended decades of Hoffa family leadership in 2022. He campaigned on a platform to take a more aggressive approach to UPS contract negotiations and to organize Amazon, the logistics giant that continues to fight union-organizing efforts. (Amazon founder Jeff Bezos also owns The Washington Post.)

“If there’s going to be a strike at UPS, it’s not going to be because of the Teamsters,” O’Brien said last week on a call with rank-and-file UPS Teamsters members. “It’s going to be because of the greediness of this company and their unwillingness to reward the people who have made them the success that they are.”

UPS maintains company officials are working to come up with a broader solution with the Teamsters.

“UPS has worked collaboratively with the Teamsters for nearly 100 years, and this year is no different. We respect this step in the process and remain committed to making progress at the bargaining table,” according to a statement on the UPS website.

The Teamsters and UPS have already reached more than two dozen tentative deals on their contract, including a landmark agreement reached Tuesday to equip new UPS package delivery vans beginning next year with air conditioning. Lack of air conditioning has been a longtime demand of delivery drivers who toil each summer in the heat for up to 14 hours a day. Older vans with also be equipped with a second fan as part of the deal.

The development of air conditioning in vans marks a resolution to a top issue at play in overall union contract negotiations but does not provide immediate relief to drivers heading into the summer months. More than 140 UPS employees have been injured in heat- or dehydration-related incidents since 2015, according to a collection of federal data reported by UPS.

UPS said that it has always been open to solutions to keep its workers safe in the heat, noting that new solutions reached this week with Teamsters will improve airflow and temperature for their employees.

The Teamsters and UPS have also already agreed to contract language that prevents UPS from implementing driverless vehicles or drones without negotiating with the union. The parties also agreed on language that would prevent the installation of driver-facing cameras in vehicles and increase UPS penalties for payroll errors.

However, for many UPS employees, the remaining issues on the bargaining table are the most important. For example, the starting pay for part-time workers who handle packages inside UPS warehouses is $15.50 an hour. Roughly half of UPS Teamsters’ positions are part-time warehouse jobs.

“This is not a sustainable wage,” said Cesar Castro, a part-time package handler in Los Angeles, who is also a member of this year’s Teamsters bargaining committee. Castro makes $18.85 an hour after nine years at UPS, which he says makes it difficult to afford basic food staples for households. “I can safely say my colleagues want better pay and more full-time jobs. We’ve broken our backs for this company.”

In a statement on its website, UPS says that part-time roles are “essential to our success,” and provide union members with industry-leading benefits including the same little-to-no-cost health insurance that full-timers receive, a pension, and tuition reimbursement.

Another sore point for Teamsters was the creation of a new class of delivery drivers in 2018 contract negotiations that make about $5 an hour less than package car drivers after four years of service. Teamsters leadership says that these two jobs are essentially the same and they want to eliminate the new class of driver.

UPS has said that the positions were introduced in agreement with the Teamsters to provide the company with more flexibility to meet consumer demand to deliver packages on Saturdays. In ongoing contract negotiations the company has declared its commitment to finding a better model “that addresses employee needs while retaining the flexibility to meet our customers’ weekend delivery needs,” the company said in a statement.

Jimi Hadley, 40, a UPS package car driver near Atlanta who makes $35 an hour after five years, said he’s prepared to go on strike if UPS does not address key issues, including better pay for part-timers, excessive overtime, and the two-tiered driver category.

“I’m not like I can’t wait to strike, but I’m absolutely prepared to stand with brothers and sisters to get whatever we deserve,” Hadley said. “We’re not asking for anything unreasonable.”

A strike at UPS this summer could severely disrupt the U.S. supply chain just as it is recovering from backlogs that weighed on the economy during the covid-19 pandemic. Major companies have already begun moving some products through FedEx and other carriers, starting this spring in anticipation of a strike later this year, according to Patrick Penfield, a professor of supply chain practice at Syracuse University.

But small companies will not have the same ability to switch over to other carriers in the case of a strike, as it’s less lucrative for carriers like FedEx to take on companies with less volume.

“This is where it gets ugly. Small companies will have a difficult time shipping,” Penfield said. “There will be long wait times for deliveries. It will push people back to shopping in stores.”

In 1997, some 185,000 UPS workers went on strike for 15 days, at the time the biggest strike in decades. The work stoppage dealt UPS severe losses, an estimated $620 million. UPS ended up conceding to many of the Teamsters’ top demands.