By STEVEN DUBOIS

Associated Press

PORTLAND, Ore. (AP) -- Longshoremen at a half-dozen Pacific Northwest grain terminals have overwhelmingly rejected what owners describe as their "last, best and final" contract offer.

Terminal owners had no immediate response to the vote Monday, but a lockout could come at any time. The owners have replacement workers standing by to ensure grain exports to Asia.

Union representatives asked the owners to return to the bargaining table and offered negotiation dates.

"The men and women of the ILWU have voted to reject the profitable grain exporters' concessionary demands, but we remain committed to reaching a fair agreement that continues our 80-year history of making these export terminals successful," Rich Austin, co-chairman of the union negotiating committee, said in a statement.

Roughly 3,000 longshoremen were eligible to vote on the contract offer and 93.8 percent rejected it, a union spokeswoman said. The last collective bargaining agreement expired Sept. 30.

More than a quarter of all U.S. grain exports and nearly half of U.S. wheat exports move through grain terminals on the Willamette River and Puget Sound. The dispute involves six of those terminals that operate under a single collective bargaining agreement with the International Longshore and Warehouse Union.

-- Japan-based Marubeni Corp. (Columbia Grain in Portland).

-- Japan-based Mitsui & Co. (United Grain in Vancouver, Wash.).

-- Netherlands-based Louis Dreyfus Commodities (grain elevators in Seattle and Portland).

-- United States-based Cargill and CHS Inc. (Temco elevators in Tacoma and Portland).

Salary and benefits have not been a sticking point during negotiations. Rather, the owners want to implement workplace rules -- or management rights -- they consider more advantageous.

The other Northwest grain terminals, based in the Washington cities of Longview and Kalama, operate under separate agreements with the ILWU. Representatives from the terminals involved in this negotiation say they are at a competitive disadvantage because the longshoremen at their facilities have more favorable rules than those in Kalama and Longview.

A copy of the confidential offer was leaked to The Oregonian last month. Concessions requested by management would allow employers to go to court to end any work stoppages immediately and to recover damages. Longshoremen would also lose some perks and grievance procedures.

"The grain exporters have not bargained in good faith, instead rejecting every effort by the union to reach a compromised settlement," said Leal Sundet, an ILWU coast committeeman. "In essence, their 'last and final' offer was not fundamentally different than that originally presented in September."

If a lockout occurs, the Coast Guard expects longshoremen to protest in boats on the Columbia and Willamette rivers. The agency has established a safety zone around all inbound and outbound grain-shipment vessels at the Columbia Grain and United Grain terminals.

Copyright 2012 The Associated Press.