Sept 9 (Reuters) - A tentative labor contract agreed

between Boeing ( BA ) and one of its biggest unions has angered

many workers who were hoping for higher wage hikes and better

pensions, an official who negotiated the deal said on Monday.

The International Association of Machinists and Aerospace

Workers (IAM), which represents more than 32,000 workers in the

U.S. Pacific Northwest, announced the deal along with Boeing ( BA ) on

Sunday, sending the aerospace giant's shares higher on Monday.

It was not clear if IAM members would vote to accept the

deal, or choose to strike when they hold a vote on Thursday,

said Jon Holden, president of the IAM's district 751 and lead

negotiator on the Boeing ( BA ) contract.

"They're angry," Holden told Reuters, adding that he

believed it was the best deal the union could get in bargaining.

"The power is within our membership on the floor," he said

when asked if he thought the deal would be ratified.

The proposed four-year contract included a general wage

increase of 25% and a commitment by Boeing ( BA ) to build its next

commercial airplane in the Seattle area, providing the plane

program was launched within the four years of the contract.

Holden said many members wanted to hold out for a 40%

pay rise over the contract period and a reinstatement of the

defined-benefit pension plan they reluctantly gave up during a

round of negotiations a decade ago.

"It's hard to come off of 10 years when you lost so many

things that were critical," Holden said.

If union workers vote down the deal and decide to

strike, it would be a blow to new Boeing ( BA ) CEO Kelly Ortberg, who

took up his role last month with a mandate to improve safety and

ramp up production of Boeing's ( BA ) best-selling 737 MAX passenger

jet.

Boeing ( BA ) is wrestling with a quality crisis and faces

scrutiny from regulators and customers, after a door plug on a

near-new MAX blew off an Alaska Air ( ALK ) jetliner while in

mid-air in January.