May 9 (Reuters) - U.S. President Joe Biden said on

Thursday he is concerned that Boeing ( BA ) has locked out its

unionized firefighters, raising pressure on the U.S. planemaker

to resolve the contract dispute.

Earlier this month, Boeing ( BA ) locked out nearly 130 members of

the International Association of Fire Fighters Local I-66 who

have rejected two contract offers.

"I'm concerned by reports that Boeing ( BA ) locked out IAFF I-66

members," Biden wrote on the social media site X. "I encourage

folks to return to the table to secure a deal that benefits

Boeing ( BA ) and gets these firefighters the pay and benefits they

deserve."

Biden's message in support of the firefighters raises the

possibility of White House involvement in separate talks between

Boeing ( BA ) and its unionized factory workers in Washington state,

two sources familiar with the matter said. Those workers produce

the planemaker's best-selling jet.

"We appreciate the support from U.S. President Joe Biden and

think it's important that he supports collective bargaining,"

said Jon Holden, president of the International Association of

Machinists and Aerospace Workers District 751 local, which

represents the Seattle-area workers.

"Our union strongly believes that collective bargaining is

the process for reaching an agreement."

The International Association of Machinists and Aerospace

Workers (IAM) is negotiating a new contract on behalf of over

30,000 workers who build Boeing's ( BA ) 737 MAX jets, at a time when

the planemaker needs to ramp up production.

Boeing 737 MAX jetliner production has fallen sharply as

U.S. regulators step up factory checks following a blowout on a

nearly new 737 MAX 9 in January, blamed on an assembly error.

Biden, who has racked up union endorsements as he runs for

re-election in November against former President Donald Trump,

has visited picket lines for the United Auto Workers (UAW). He

considers support for labor to be a cornerstone of his economic

policies.

The votes of union members could be crucial to deciding the

2024 election in key swing states like Michigan, Pennsylvania,

Nevada and Wisconsin.

"Imagine if he'd throw his hat in for the IAM," said one

investor who spoke on condition of anonymity.

Boeing ( BA ) has said its latest offer, which would increase

firefighters' take-home pay from $91,000 on average to $112,000

on average in the first year of the contract, remains on the

table.

"We remain committed to securing an agreement. Our offer

provides significant pay increases and increased benefits,"

Boeing ( BA ) said in a statement. "The union should allow our

employees to vote (on) our offer, which was presented before the

lockout."

IAFF General President Edward Kelly said the firefighters

are "are grateful that the President stands up for collective

bargaining" and continues to have their backs.