* Stalemate fuels speculation of possible lockout of workers
* Coast Guard prepares for potential waterfront labor unrest
* Union calls on grain shippers to return to bargaining table (Adds details, background, byline)
By Laura L. Myers
SEATTLE, Dec 24 (Reuters) - Dockworkers at four ports in the U.S. Pacific Northwest voted overwhelmingly to reject a "final" contract offer presented by grain shippers, their union said on Monday, setting the stage for a possible labor clash that could hamper exports from the region.
The stalemate in contract talks, and management's failure to win approval of its offer, fueled speculation that the shipping companies might move to impose a lockout of union members in a bid to keep grain terminals operating with replacement workers.
There was no immediate comment from the Pacific Northwest Grain Handlers Association, which represents the shipping companies and the grain terminals they own, on the outcome of the union vote.
The International Longshore and Warehouse Union (ILWU) has said the shippers have hired a Delaware-based company that specializes in providing security and replacement workers in labor disputes.
The U.S. Coast Guard said last week it was preparing to establish buffer zones to keep union-related protests from interfering with navigation around two of the ports seen as most likely to be caught up in waterborne labor unrest.
The possibility of a labor showdown in the Northwest comes as ports along the U.S. Atlantic and Gulf coasts brace for a separate strike threatened for Dec. 30 by union dock workers unless shippers extend their contract.
Weeks ago, harbor clerks and union longshoremen honoring their picket lines staged an eight-day walkout in Southern California at the twin ports of Los Angeles and Long Beach, idling much of the nation's busiest cargo-shipping complex.
Rich Austin, co-chairman of the negotiating committee for the ILWU, said in a statement the union remains "committed to reaching a fair agreement" and called for grain exporters to "return to the negotiating table."
Both sides have declined to discuss in detail the points of contention that have blocked a settlement.
Votes on a contract proposal that management called its "last, best and final" offer were cast Friday and Saturday by nearly 3,000 union members in Portland, Oregon, and in Seattle, Tacoma and Vancouver, Washington.
According to the final tally announced on Monday, 93.8 percent of those voting disapproved the proposal, as recommended by union leaders, and 6.2 percent voted to accept it.
The proposed contract covers six of the nine grain terminals operating in the Puget Sound and along the Columbia River that the industry says account for more than a quarter of all U.S. grain exports and nearly half of U.S. wheat exports.
SWITCHING FROM BARGES TO TRAINS?
Waterfront labor strife in the Northwest would compound an existing slowdown in U.S. grain exports caused by the low water levels on the Mississippi River by making it harder for shippers to meet expectations set by the U.S. Agriculture Department, said Bob Utterback, of Utterback Marketing Services, a brokerage for farmers.
Pendleton Grain Growers, for example, the largest cooperative grain dealer in Oregon, will likely overhaul its shipping plans to send more wheat, corn and soybeans to ports via railroad instead of barges, said Jason Middleton, director of grain operations for the cooperative.
Such a switch could slow shipments, most of which normally are sent up the Columbia River en route to Asia.
The old contact for dockworkers at the six terminals expired on Sept. 30, but under terms that remain in effect for the time being, regular work shifts for ILUW members end at 3 p.m. local time Monday, and union workers have the day off on Tuesday for the Christmas holiday.
The shipping companies say the chief issue is "beneficial work rules" that will give them a cost advantage over competitors. A spokesman last week said shippers were seeking the same workplace rules and terms the union had agreed to after lengthy and contentious labor talks with EGT, an exporter that opened a new terminal last year in Longview, Washington.
The ILWU cited 750 changes it said the companies were seeking to impose on labor contract terms that have stood for more than 80 years.
The Portland Oregonian newspaper reported last month that the companies' latest contract offer heavily favors the shippers by eliminating many longshoremen's perks such as 30-minutes' pay for working six minutes into an hour and compensation while conducting union business at work. It also would abolish grievance procedures for workers who oppose equipment modernization. (Reporting by Laura L. Myers in Seattle; Additional reporting by Christine Stebbins and Tom Polansek in Chicago, and Teresa Carson in Portland, Ore.; Writing by Steve Gorman; Editing by Bob Burgdorfer and Leslie Adler)