White House officials met Friday with port operators and urged them to negotiate with a longshoremen’s union just days before a strike deadline that threatens to shut down ports in Baltimore and along the East and Gulf Coasts.

Transportation Secretary Pete Buttigieg, Acting Labor Secretary Julie Su and Lael Brainard, director of the White House National Economic Council, told members of the United States Maritime Alliance that they should be at the table with the union and negotiating ahead of the contract expiring Monday, according to a White House official who insisted on anonymity.

Biden administration officials delivered a similar message to the International Longshoremen’s Association this week.

Friday’s meeting came a day after port operators took steps to force the union to resume bargaining.

The Maritime Alliance filed an unfair labor practice charge Thursday with the National Labor Relations Board, accusing the longshoremen of refusing to come to the table to negotiate.

The Maritime Alliance said it wants to intervene “due to the ILA’s repeated refusal to come to the table and bargain on a new Master Contract.”

“USMX has been clear that we value the work of the ILA and have great respect for its members,” said the group, which represents shipping lines and marine terminal operators, in a statement. “We have a shared history of working together and are committed to bargaining.”

The dockworkers union fired back, calling the federal filing a publicity stunt. Harold J. Daggett, the ILA’s international president and chief negotiator, disputed alliance statements earlier this week, saying “the two sides have communicated multiple times in recent weeks.”

When unfair labor charges are filed, the NLRB typically must investigate to determine whether formal action is needed, a process than can take weeks. The NLRB could issue a complaint and hold a hearing before an administrative law judge or ask the court for a restraining order.

An NLRB spokesperson did not respond Friday to a request for comment.

A strike by Baltimore dockworkers would shut down the city’s port for the second time this year. Baltimore’s maritime facilities are still recovering from a shipping channel closure of more than two months after the cargo ship Dali hit the Francis Scott Key Bridge. The March 26 accident caused the span to collapse and killed six roadway workers

The ILA has 85,000 members. In Baltimore, three ILA union locals represent about 2,400 workers, who load and unload all ships in port. The Maryland Port Administration, the state agency that oversees Baltimore’s six state-owned marine terminals, is not a party to the ILA contract but has been monitoring talks.

A port administration spokesman said Friday that Ports America Chesapeake, which operates Seagirt Marine Terminal, has extended its hours ahead of the strike deadline and will be open Saturday from 7 a.m. until 11 a.m. to handle trucks.

Normally Seagirt, the port’s main container terminal, is open Monday through Friday.

The union said the employer group’s latest move is part of a “weak publicity campaign designed to fool the American public that they care for the longshore workers who help earn them billions of dollars and are serious about negotiating a new Master Contract Agreement.”

It said foreign-owned companies, represented by the Maritime Alliance, are based at U.S. ports, earn billions of dollars in revenues and profits but fail to adequately compensate the ILA longshore workforce from Maine through Texas. The workers also object to new technologies that would automate some work and could cause job losses.

The union says it is prepared to strike if no agreement is reached by Monday.

The employers’ group said in its statement that the labor board could require the union to bargain “so that we can negotiate a deal.”

The two sides first met for “exploratory” talks on the so-called master contract more than two years ago.

While some retailers and importers have been preparing for months for a stoppage, scheduling earlier deliveries or diverting shipments to the West Coast, an extended strike is expected to have dire and widespread economic consequences.

Port-related economic losses on the East and Gulf coasts could add up to as much as $5 billion a day, Margaret Kidd, an instructional associate professor of supply chain and logistics technology at the University of Houston, said this week.

For every day the ILA is on strike, it would take an average five days to clear backlogs, which means a two-week strike could have implications into next year. Ultimately, prices would rise for manufacturers, shippers and consumers.

“It really becomes a potential economic tsunami to hit the U.S., if there’s a strike that goes beyond a few days,” Kidd said.

ILA has not walked out on such a large-scale on the East Coast since 1977, when a work stoppage lasted 45 days.

The Associated Press contributed to this story.