Contract talks between West Coast dockworkers and shipping lines are in danger of breaking down, according to a report from CNBC, creating nervousness for retailers as the holiday season approaches. Analysts have said that even a short port strike could have far-reaching consequences for the U.S. economy, with trade groups estimating that a 10-day stoppage could cost the country $21 billion and 169,000 jobs.

“If there is a walkout or lockout, it’s a disaster for everybody,” said Bruce Carlton, president of the National Industrial Transportation League, a lobby group for manufacturers.

Nearly 20,000 dockworkers at 29 West Coast ports have been without a contract since July 1.  Negotiations have been ongoing, and some progress was reported in August when the two sides announced a tentative agreement on health-care benefits. But the talks are beginning to show strain and frustration is brimming over into public view. The Pacific Maritime Association, which represents ship lines and other terminal operators, issued a statement this week accusing the dock workers union of initiating “orchestrated slowdowns at the Pacific Northwest ports of Seattle and Tacoma, severely impacting many of the largest terminals during the peak holiday shopping season.”

The International Longshoremen and Warehouseman’s Union said in response: “PMA’s media offensive is designed to smear the union and to deflect responsibility from a growing congestion problem that is plaguing major West Coast ports.”

More than half of the freight moving into and out of the U.S. goes through the West Coast, affecting anyone importing goods, including ad specialty firms. Congestion at the ports has been growing in recent months, in part because importers have been boosting shipments to build up holiday inventories in case of a breakdown in talks.

Spokespeople from both sides told CNBC that talks were scheduled to resume Wednesday. Manufacturers and retailers, meanwhile, are growing tired of the lack of progress: “We’re appreciative that they’ve stayed at the negotiating table since May,” Carlton told CNBC. “The problem is, this is November. I mean, how hard is this?”