More than 100 groups that are concerned about the direction of newly contentious West Coast port contract talks asked President Obama to name a federal mediator to foster a settlement.

“While the parties to the negotiation stated earlier this year that they would continue operations throughout the negotiations, we have seen crisis levels of congestion at the ports since September,” said the letter signed by American Trucking Associations, the National Retail Federation and the Transportation Intermediaries Association. “Both parties recently issued press releases accusing each other of reneging on this commitment.”

Earlier this week, the Pacific Maritime Association, the management negotiators representing ocean carriers and terminal operators, claimed the International Longshore & Warehouse Union orchestrated slowdowns in Pacific Northwest ports. After the union denied that was the first public outburst since talks began, PMA said similar disruptions began in Los Angeles and Long Beach, the largest U.S. ports.

“The sudden change in tone is alarming and suggests that a full shutdown of every West Coast port may be imminent,” said the letter, also signed by the Retail Industry Leaders Association and groups representing importers of goods including shoes and wood products. “The impact this would have on jobs, downstream consumers, and the business operations of exporters, importers, retailers, transportation providers, manufacturers and other stakeholders would be catastrophic.”

There was no immediate comment from the White House.

The six-year port contract expired July 1. Talks began six months ago. The groups expressed concern that there could be a repetition of a 2002 lockout, which for 10 days paralyzed freight transport in the world’s largest consumer market.