DETROIT — Ron Gettelfinger didn't mention concessions in his opening speech to the United Auto Workers bargaining convention yesterday, but many others were speaking the word in and out of the meeting hall.

The UAW president, facing what many say will be the toughest contract talks with Detroit's Big Three automakers in union history, warned companies that the UAW would strike if necessary, and he reassured members that it would protect their interests as DaimlerChrysler AG places its U.S. unit up for sale.

But across the street and on the floor of the downtown Detroit convention center, union members debated whether they should give anything back to companies, especially those who have granted bonuses to executives.

"The upper management continues to get their bonuses. They continue to take work overseas no matter what the worker does," said Phil Doyle, a delegate from an Allison Transmission plant near Indianapolis who is against granting any wage cuts, healthcare givebacks or other concessions.

But Dennis Bryan, a delegate who retired from a former Ford Motor Co. and Visteon Corp. plant in Saline, said the union has to be flexible according to a particular plant's situation.

Bryan's former plant is now part of a holding company and awaiting sale or closure, and he said there are times when concessions may be necessary to keep a plant competitive.

While he, too, is upset with executive bonuses, he wouldn't rule out giving back something to save a plant from closure or help a troubled company.

"We've always been about keeping a company viable so we can earn decent wages," Bryan said.

The two men represent conflicting views among the 1,500 or so members attending the two-day convention, and they also present a challenge to Gettelfinger as he leads the union into the formal start of bargaining with the Detroit Three this summer.

Gettelfinger sounded a defiant tone in his opening remarks, saying that the union doesn't want to strike, but would if necessary.

"We will do what we have to do," he said. "Make no mistake about it: Collective bargaining is not collective begging, and where we have demonstrated cooperation it would be a grave mistake to equate our actions to capitulation."

The convention delegates, from more than 800 UAW locals in the U.S. and Canada, weren't expected to get into the nitty-gritty of what will be discussed with individual companies.

Still, the UAW is facing crucial contract talks that formally start this summer, although meetings already have begun. The national UAW contract with automakers expires in September.

In his speech, Gettelfinger acknowledged that the UAW has faced continued challenges since its last bargaining convention in 2002, citing DaimlerChrysler AG's February announcement that it would consider selling its U.S.-based Chrysler unit.

"We have equity and hedge funds circling our head as never before," he said of potential buyers for Chrysler.

Gettelfinger accused the funds of "stripping and flipping" companies they buy.

"Our union is on guard to protect the best interests of our membership," he said.

Outside the convention center, about 20 members and retirees carried signs in protest of concessions.

One delegate, Mike Parker, a worker at Chrysler's Sterling Heights assembly plant, made a motion to change today's agenda to set aside time for organizing local leaders to fight back against companies that are demanding concessions plant by plant.

"The problem is the locals are being left to bargain by themselves in dealing with the companies," he said in an interview.

The motion was shot down by a voice vote, but others made similar speeches about zero concessions and bringing an end to a two-tier wage scale in which new hires are paid far less than older workers.

The UAW's main employers — General Motors Corp., Chrysler and Ford Motor Co. — have lost billions during the past two years and are expected to demand major concessions from the UAW in contract talks this summer. The UAW master contract with the Detroit Three ends in September.

Among the issues are healthcare costs for active and retired workers; wages; work rules; and the jobs bank, in which laid-off workers get most of their pay.