The Pacific Maritime Association, which represents employers at America’s 29 West Coast ports, on Monday asked for federal mediation in its contract negotiations with the International Longshore and Warehouse Union.

The two sides have been in contract talks since early this year, but have been unable to iron out a new agreement, though dockworkers have remained on the job.

“While a number of observers, including policy-makers, retailers and port directors; have previously called for mediation, PMA had hoped the parties could reach resolution without outside aid,” PMA said in a statement.

“After the latest back-and-forth between the parties failed to resolve their differences, however, PMA has now agreed that outside intervention is necessary to bring the talks to conclusion, particularly given the ongoing impact of ILWU work slowdowns, which have disrupted cargo movement at the major West Coast ports of Tacoma, Seattle, Oakland, Los Angeles and Long Beach.”

According to the PMA, the union’s continued actions are creating long-term damage to the West Coast port operations, causing the facilities to lose market share to ports on the U.S. East and Gulf coasts.

A recent industry survey conducted by the Journal of Commerce showed 60% of shippers have already rerouted cargo for 2015 away from the U.S. West Coast to avoid the problems, with many saying their diversions will be permanent.

“After seven months of negotiations, we remain far apart on many issues,” said PMA spokesman Wade Gates. “At the same time, the union continues its slowdowns, walk-offs and other actions that are having impacts on shippers, truck drivers and other local workers, with no end in sight. It is clear that the parties need outside assistance to bridge the substantial gap between us.”

The ILWU has denied its engaged in any work slowdowns and has blamed problems at West Coast ports on poor scheduling and management, though there have been brief walkouts by workers at some facilities.

Regardless of the reasons, trucking operations and drivers serving the ports, have complained they have faced increased wait times for picking up and delivering freight, among other problems.