UPS Inc. and the Teamsters union will resume national bargaining June 5 as both sides spend the week negotiating the final two supplemental agreements covering workers in Louisville, Kentucky, and Northern California.

The hiatus comes as both sides reached a tentative agreement to reduce the size of UPS SurePost packages eligible for handoff to the U.S. Postal Service, according to a report in Supply Chain Dive confirmed by a Teamsters spokesperson. The agreement, which must be ratified by the Teamsters rank and file, will increasingly redirect more SurePost packages to regular package car drivers over the life of the contract, the spokesperson said. No details were provided.

In an email to FreightWaves, Kara Deniz said that “we’ve reached (a) tentative agreement … to reduce the overall size of packages eligible for SurePost delivery — so more existing volume is going back onto Teamster trucks rather than coming off.”

Under terms of the current contract, a package handled by the Postal Service must meet certain weight and cubic criteria to move as SurePost. If they are exceeded, the package is eligible to be redirected into the UPS system for delivery by a union driver.

In a communique last week, the union said it had spent hours “repeatedly pushing back on attempts to weaken worker protections around the SurePost program.” Several rounds of proposals were exchanged to push UPS to agree to put more boxes on union package cars, the Teamsters said.

Under SurePost, lightweight packages bound for residences are inducted deep into the postal system for final-mile delivery by letter carriers. The Teamsters have long pushed to get rid of SurePost because it siphons delivery business from its members.